13 fractions, multiplication and divisin of fractions

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Page 1: 13 fractions, multiplication and divisin of fractions

Fractions

Page 2: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers.

pq

Fractions

Page 3: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers.

pq

Fractions

36

Page 4: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers. Fractions are numbers that measure parts of whole items.

pq

Fractions

36

Page 5: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers. Fractions are numbers that measure parts of whole items.Suppose a pizza is cut into 6 equal slices and we have 3 ofthem, the fraction that represents this quantity is .

pq

36

Fractions

36

Page 6: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers. Fractions are numbers that measure parts of whole items.Suppose a pizza is cut into 6 equal slices and we have 3 ofthem, the fraction that represents this quantity is .

pq

36

36

Fractions

Page 7: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers. Fractions are numbers that measure parts of whole items.Suppose a pizza is cut into 6 equal slices and we have 3 ofthem, the fraction that represents this quantity is .

pq

36

The bottom number is the number of equal parts in the division and it is called the denominator.

36

Fractions

Page 8: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers. Fractions are numbers that measure parts of whole items.Suppose a pizza is cut into 6 equal slices and we have 3 ofthem, the fraction that represents this quantity is .

pq

36

The bottom number is the number of equal parts in the division and it is called the denominator.

36

Fractions

Page 9: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers. Fractions are numbers that measure parts of whole items.Suppose a pizza is cut into 6 equal slices and we have 3 ofthem, the fraction that represents this quantity is .

pq

36

The bottom number is the number of equal parts in the division and it is called the denominator.

The top number “3” is the number of parts that we have and it is called the numerator.

36

Fractions

Page 10: 13 fractions, multiplication and divisin of fractions

Fractions are numbers of the form (or p/q) where p, q 0 are whole numbers. Fractions are numbers that measure parts of whole items.Suppose a pizza is cut into 6 equal slices and we have 3 ofthem, the fraction that represents this quantity is .

pq

36

The bottom number is the number of equal parts in the division and it is called the denominator.

The top number “3” is the number of parts that we have and it is called the numerator.

36

Fractions

3/6 of a pizza

Page 11: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

Page 12: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

How many slices should we cut the pizza into and how do we do this?

Page 13: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

Cut the pizza into 8 pieces,

Page 14: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

Cut the pizza into 8 pieces, take 5 of them.

Page 15: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

5/8 of a pizza

Cut the pizza into 8 pieces, take 5 of them.

Page 16: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

Page 17: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

Cut the pizza into 12 pieces,

Page 18: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

Cut the pizza into 12 pieces,

Page 19: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

Cut the pizza into 12 pieces, take 7 of them.

Page 20: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

Cut the pizza into 12 pieces, take 7 of them.

or

Page 21: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

7/12 of a pizza

or

Cut the pizza into 12 pieces, take 7 of them.

Page 22: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

Note that or is the same as 1.88

1212

7/12 of a pizza

or

Page 23: 13 fractions, multiplication and divisin of fractions

For larger denominators we can use a pan–pizza for pictures. For example,

58

Fractions

712

5/8 of a pizza

Fact: aa

Note that or is the same as 1.88

1212

= 1 (provided that a = 0.)

7/12 of a pizza

or

Page 24: 13 fractions, multiplication and divisin of fractions

FractionsWe may talk about the fractional amount of a group of items.

Page 25: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

Page 26: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

Page 27: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

34 Divide $100 into

4 equal parts.

Page 28: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

34 Divide $100 into

4 equal parts.

100 ÷ 4 = 25 so each part is $25,

Page 29: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

34 Divide $100 into

4 equal parts.

Take 3 parts. 100 ÷ 4 = 25 so each part is $25,

Page 30: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

34 Divide $100 into

4 equal parts.

Take 3 parts. 100 ÷ 4 = 25 so each part is $25,3 parts make $75. So ¾ of $100 is $75.

Page 31: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

34 Divide $100 into

4 equal parts.

Take 3 parts. 100 ÷ 4 = 25 so each part is $25,3 parts make $75. So ¾ of $100 is $75.

712

Divide 72 people into 12 equal parts.

Page 32: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

34 Divide $100 into

4 equal parts.

Take 3 parts. 100 ÷ 4 = 25 so each part is $25,3 parts make $75. So ¾ of $100 is $75.

712

Divide 72 people into 12 equal parts.

72 ÷ 12 = 6 so each part consists of 6 people,

Page 33: 13 fractions, multiplication and divisin of fractions

Fractions

Example A. a. What is ¾ of $100?

We may talk about the fractional amount of a group of items.To calculate such amounts, we always divide the group into parts indicated by the denominator, then retrieve the number of parts indicated by the numerator.

b. Out of an audience of 72 people at a movie, 7/12 of them like the show very much. How many people is that?

34 Divide $100 into

4 equal parts.

Take 3 parts. 100 ÷ 4 = 25 so each part is $25,3 parts make $75. So ¾ of $100 is $75.

712

Divide 72 people into 12 equal parts.

Take 7 parts. 72 ÷ 12 = 6 so each part consists of 6 people,7 parts make 42 people. So 7/12 of 92 people is 42 people.

Page 34: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Fractions

Page 35: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = .

51

x1

Fractions

Page 36: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

51

x1

0x

Fractions

Page 37: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

Page 38: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:

Page 39: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0.

Page 40: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0. (It's undefined if the denominator is 0.)

Page 41: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0. (It's undefined if the denominator is 0.)Fractions that represents the same quantity are called equivalent fractions.

Page 42: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0. (It's undefined if the denominator is 0.)Fractions that represents the same quantity are called equivalent fractions. 12 =

24

Page 43: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0. (It's undefined if the denominator is 0.)Fractions that represents the same quantity are called equivalent fractions. 12 =

24 =

36

Page 44: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0. (It's undefined if the denominator is 0.)Fractions that represents the same quantity are called equivalent fractions. … are equivalent fractions.12 =

24 =

36 =

48

Page 45: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0. (It's undefined if the denominator is 0.)Fractions that represents the same quantity are called equivalent fractions. … are equivalent fractions.

The fraction with the smallest denominator of all the equivalent fractions is called the reduced fraction.

12 =

24 =

36 =

48

Page 46: 13 fractions, multiplication and divisin of fractions

Whole numbers can be viewed as fractions with denominator 1. Thus 5 = and x = . The fraction = 0, where x 0.

However, does not have any meaning, it is undefined.

51

x1

0x

x0

Fractions

The Ultimate No-No of Mathematics:The denominator (bottom) of a fraction can't be 0. (It's undefined if the denominator is 0.)Fractions that represents the same quantity are called equivalent fractions. … are equivalent fractions.

The fraction with the smallest denominator of all the equivalent fractions is called the reduced fraction.

12 =

24 =

36 =

48

is the reduced one in the above list.12

Page 47: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.

ab

ab = a / c

Fractions

b / c

Page 48: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1,

ab

ab = a / c

Fractions

b / c

Page 49: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

=a*cb*c

a*cb*c

1

Fractions

b / c

Page 50: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Page 51: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

(Often we omit writing the 1’s after the cancellation.)

Page 52: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

(Often we omit writing the 1’s after the cancellation.)

Page 53: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Example B. Reduce the fraction . 7854

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

(Often we omit writing the 1’s after the cancellation.)

Page 54: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Example B. Reduce the fraction . 7854

7854

=

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

(Often we omit writing the 1’s after the cancellation.)

Page 55: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Example B. Reduce the fraction . 7854

7854

= 78/254/2

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

(Often we omit writing the 1’s after the cancellation.)

Page 56: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Example B. Reduce the fraction . 7854

7854

= 78/254/2

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

=39

27

(Often we omit writing the 1’s after the cancellation.)

Page 57: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Example B. Reduce the fraction . 7854

7854

= 78/254/2

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

= 39/327/3

39

27

(Often we omit writing the 1’s after the cancellation.)

Page 58: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Example B. Reduce the fraction . 7854

7854

= 78/254/2

= 139 .

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

= 39/327/3

39

27

(Often we omit writing the 1’s after the cancellation.)

Page 59: 13 fractions, multiplication and divisin of fractions

Factor Cancellation RuleGiven a fraction , then

that is, if the numerator and denominator are divided by the same quantity c, the result will be an equivalent fraction.In other words, a common factor of the numerator and the

denominator may be canceled as 1, i.e.

ab

ab = a / c

ab .=a*c

b*c =a*cb*c

1

Fractions

b / c

Example B. Reduce the fraction . 7854

7854

= 78/254/2

= 139 .

To reduce a fraction, we keep divide the top and bottom by common numbers until no more division is possible. What's left is the reduced version.

= 39/327/3

or divide both by 6 in one step.

39

27

(Often we omit writing the 1’s after the cancellation.)

Page 60: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

Page 61: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.A participant in a sum or a difference is called a term.

Page 62: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression).

Page 63: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor.

Page 64: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 65: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

35

=

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 66: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

35

=

This is addition. Can’t cancel!

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 67: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

= 2 + 1 2 + 3

35

=

This is addition. Can’t cancel!

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 68: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

= 2 + 1 2 + 3

= 13

35

=

This is addition. Can’t cancel!

!?

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 69: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

= 2 + 1 2 + 3

= 13

35

=

This is addition. Can’t cancel!

!? 2 * 12 * 3 = 1

3Yes

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 70: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

= 2 + 1 2 + 3

= 13

35

=

This is addition. Can’t cancel!

!?

Improper Fractions and Mixed Numbers

2 * 12 * 3 = 1

3Yes

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 71: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

= 2 + 1 2 + 3

= 13

35

=

This is addition. Can’t cancel!

!?

A fraction whose numerator is the same or more than its denominator (e.g. ) is said to be improper .

Improper Fractions and Mixed Numbers

3 2

2 * 12 * 3 = 1

3Yes

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 72: 13 fractions, multiplication and divisin of fractions

FractionsOne common mistake in cancellation is to cancel a common number that is part of an addition (or subtraction) in the numerator or denominator.

2 + 12 + 3

= 2 + 1 2 + 3

= 13

35

=

This is addition. Can’t cancel!

!?

A fraction whose numerator is the same or more than its denominator (e.g. ) is said to be improper .We may put an improper fraction into mixed form by division.

Improper Fractions and Mixed Numbers

3 2

2 * 12 * 3 = 1

3Yes

A participant in a sum or a difference is called a term. The “2” in the expression “2 + 3” is a term (of the expression). The “2” is in the expression “2 * 3” is called a factor. Terms may not be cancelled. Only factors may be canceled.

Page 73: 13 fractions, multiplication and divisin of fractions

23 4

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

Page 74: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. ··

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

Page 75: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. Hence, ··

23 4

= 5 +

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

3 4

Page 76: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. Hence, ··

23 4

= 5 + 5 3 4 .

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

3 4

=

Page 77: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. Hence, ··

23 4

= 5 + 5 3 4 .

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

3 4

=

We may put a mixed number into improper fraction by doing the reverse via multiplication.

Page 78: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. Hence, ··

23 4

= 5 + 5 3 4 .

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

3 4

=

We may put a mixed number into improper fraction by doing the reverse via multiplication.

Example D. Put into improper form. 5 3 4

Page 79: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. Hence, ··

23 4

= 5 + 5 3 4 .

5 3 4

= 4*5 + 3 4

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

3 4

=

We may put a mixed number into improper fraction by doing the reverse via multiplication.

Example D. Put into improper form. 5 3 4

Page 80: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. Hence, ··

23 4

= 5 + 5 3 4 .

5 3 4

= 4*5 + 3 4

23 4=

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

3 4

=

We may put a mixed number into improper fraction by doing the reverse via multiplication.

Example D. Put into improper form. 5 3 4

Page 81: 13 fractions, multiplication and divisin of fractions

23 4

23 4 = 5 with remainder 3. Hence, ··

23 4

= 5 + 5 3 4 .

5 3 4

= 4*5 + 3 4

23 4=

Improper Fractions and Mixed NumbersExample C. Put into mixed form.

3 4

=

We may put a mixed number into improper fraction by doing the reverse via multiplication.

Example D. Put into improper form. 5 3 4

Page 82: 13 fractions, multiplication and divisin of fractions

Rule for Multiplication of FractionsMultiplication and Division of Fractions

Page 83: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 84: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

1225

158

*a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 85: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 86: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 87: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 88: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3=

3*32*5

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 89: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 90: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

b.89

78

*1011

910

**

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 91: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

7*8*9*10

8*9*10*11b.

89

78

*1011

910

** =

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 92: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

7*8*9*10

8*9*10*11b.

89

78

*1011

910

** =

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 93: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

7*8*9*10

8*9*10*11b.

89

78

*1011

910

** =

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 94: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

7*8*9*10

8*9*10*11b.

89

78

*1011

910

** =

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Each set of cancellation produces a “1”, which does not affect final the product.

Multiplication and Division of Fractions

Page 95: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

7*8*9*10

8*9*10*11b.

89

78

*1011

910

** = =711

a.

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 96: 13 fractions, multiplication and divisin of fractions

cd

=a*cb*d

ab

*

Example E. Multiply by reducing first.

=15 * 12 8 * 25

1225

158

*2

3

5

3= =

910

3*32*5

7*8*9*10

8*9*10*11b.

89

78

*1011

910

** = =711

a.

Can't do this for addition and subtraction, i.e.cd

= a cb d

ab

±±±

Rule for Multiplication of FractionsTo multiply fractions, multiply the numerators and multiply the denominators, but always cancel as much as possible first then multiply.

Multiplication and Division of Fractions

Page 97: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

The fractional multiplications are important.or * *

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 98: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 a.

The fractional multiplications are important.or * *

*

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 99: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 a.

The fractional multiplications are important.

6

or * *

*

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 100: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 a.

The fractional multiplications are important.

6

or * *

* *

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 101: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

or * *

* *

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 102: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.

or * *

* *

*

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 103: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

*

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 104: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

* = 3 * 11

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 105: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

* = 3 * 11 = 33

Often in these problems the denominator b can be cancelledagainst d = .

Multiplication and Division of Fractions

Page 106: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

* = 3 * 11 = 33

Often in these problems the denominator b can be cancelledagainst d = .

The often used phrases " (fraction) of .." are translated to multiplications correspond to this kind of problems.

Multiplication and Division of Fractions

Page 107: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

* = 3 * 11 = 33

Often in these problems the denominator b can be cancelledagainst d = .

The often used phrases " (fraction) of .." are translated to multiplications correspond to this kind of problems.

Example G. a. What is of $108?23

Multiplication and Division of Fractions

Page 108: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

* = 3 * 11 = 33

Often in these problems the denominator b can be cancelledagainst d = .

The often used phrases " (fraction) of .." are translated to multiplications correspond to this kind of problems.

Example G. a. What is of $108?23

* 108 23The statement translates into

Multiplication and Division of Fractions

Page 109: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

* = 3 * 11 = 33

Often in these problems the denominator b can be cancelledagainst d = .

The often used phrases " (fraction) of .." are translated to multiplications correspond to this kind of problems.

Example G. a. What is of $108?23

* 108 23

36The statement translates into

Multiplication and Division of Fractions

Page 110: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

or * *

* *

* = 3 * 11 = 33

Often in these problems the denominator b can be cancelledagainst d = .

The often used phrases " (fraction) of .." are translated to multiplications correspond to this kind of problems.

Example G. a. What is of $108?23

* 108 = 2 * 36 23

36The statement translates into

Multiplication and Division of Fractions

Page 111: 13 fractions, multiplication and divisin of fractions

ab d a

bd

d1

Example F. Multiply by cancelling first.23 18 = 2 6 = 12a.

The fractional multiplications are important.

6

1116

48

b.3

Multiplication and Division of Fractionsor * *

* *

* = 3 * 11 = 33

Often in these problems the denominator b can be cancelledagainst d = .

The often used phrases " (fraction) of .." are translated to multiplications correspond to this kind of problems.

Example G. a. What is of $108?23

* 108 = 2 * 36 = 72 $.23

36The statement translates into

Page 112: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

Multiplication and Division of Fractions

Page 113: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

For chocolate, ¼ of 48 is 14

* 48

Multiplication and Division of Fractions

Page 114: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

For chocolate, ¼ of 48 is 14

* 48 = 12,12

Multiplication and Division of Fractions

Page 115: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

For chocolate, ¼ of 48 is 14

* 48 = 12,12

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 116: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 isso there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 117: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16, so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 118: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 119: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.The rest 48 – 12 – 16 = 20 are lemon drops.

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 120: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.The rest 48 – 12 – 16 = 20 are lemon drops. The fraction of the lemon drops is 20

48

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 121: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.The rest 48 – 12 – 16 = 20 are lemon drops. The fraction of the lemon drops is 20

48 = 20/448/4

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 122: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.The rest 48 – 12 – 16 = 20 are lemon drops. The fraction of the lemon drops is 20

48 = 20/448/4 = 5

12

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 123: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

c. A class has x students, ¾ of them are girls, how many girls are there?

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.The rest 48 – 12 – 16 = 20 are lemon drops. The fraction of the lemon drops is 20

48 = 20/448/4 = 5

12

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 124: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

c. A class has x students, ¾ of them are girls, how many girls are there?

34 * x.

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.The rest 48 – 12 – 16 = 20 are lemon drops. The fraction of the lemon drops is 20

48 = 20/448/4 = 5

12

It translates into multiplication as

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 125: 13 fractions, multiplication and divisin of fractions

b. A bag of mixed candy contains 48 pieces of chocolate, caramel and lemon drops. 1/4 of them are chocolate, 1/3 of them are caramel. How many pieces of each are there? What fraction of the candies are lemon drops?

13

* 48 16

c. A class has x students, ¾ of them are girls, how many girls are there?

34 * x.

For chocolate, ¼ of 48 is 14

* 48 = 12,12

For caramel, 1/3 of 48 is = 16,

so there are 16 pieces of caramel candies.The rest 48 – 12 – 16 = 20 are lemon drops. The fraction of the lemon drops is 20

48 = 20/448/4 = 5

12

It translates into multiplication as

so there are 12 pieces of chocolate candies.

Multiplication and Division of Fractions

Page 126: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Page 127: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

So the reciprocal of is , 23

32

Page 128: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5

Page 129: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5the reciprocal of is 3, 1

3

Page 130: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

Page 131: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About Reciprocals

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

Page 132: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

Page 133: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32* = 1,

Page 134: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32* = 1, 5 1

5* = 1,

Page 135: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32* = 1, 5 1

5* = 1, x 1x* = 1,

Page 136: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32*

II. Dividing by x is the same as multiplying by its reciprocal .

= 1, 5 15* = 1, x 1

x* = 1,1x

Page 137: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32*

II. Dividing by x is the same as multiplying by its reciprocal .

= 1, 5 15* = 1, x 1

x* = 1,1x

For example, 10 ÷ 2 is the same as 10 , *12

Page 138: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32*

II. Dividing by x is the same as multiplying by its reciprocal .

= 1, 5 15* = 1, x 1

x* = 1,1x

For example, 10 ÷ 2 is the same as 10 , both yield 5. *12

Page 139: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32*

II. Dividing by x is the same as multiplying by its reciprocal .

= 1, 5 15* = 1, x 1

x* = 1,1x

For example, 10 ÷ 2 is the same as 10 , both yield 5. *12

Rule for Division of FractionsTo divide by a fraction x, restate it as multiplying by the reciprocal 1/x , that is,

Page 140: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32*

II. Dividing by x is the same as multiplying by its reciprocal .

= 1, 5 15* = 1, x 1

x* = 1,1x

For example, 10 ÷ 2 is the same as 10 , both yield 5. *12

Rule for Division of FractionsTo divide by a fraction x, restate it as multiplying by the reciprocal 1/x , that is, d

cab *

cd = a

b ÷reciprocate

Page 141: 13 fractions, multiplication and divisin of fractions

The reciprocal (multiplicative inverse) of is . ab

ba

Reciprocal and Division of Fractions

Two Important Facts About ReciprocalsI. The product of x with its reciprocal is 1.

So the reciprocal of is , 23

32 the reciprocal of 5 is , 1

5and the reciprocal of x is . 1

xthe reciprocal of is 3, 13

23

32*

II. Dividing by x is the same as multiplying by its reciprocal .

= 1, 5 15* = 1, x 1

x* = 1,1x

For example, 10 ÷ 2 is the same as 10 , both yield 5. *12

Rule for Division of FractionsTo divide by a fraction x, restate it as multiplying by the reciprocal 1/x , that is, d

c = a*db*c

ab *

cd = a

b ÷reciprocate

Page 142: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

815

= 1225

a. ÷

Reciprocal and Division of Fractions

Page 143: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

1225

*8

15 =

1225

a. ÷

Reciprocal and Division of Fractions

Page 144: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

1225

*8

15 =

1225 2

3a. ÷

Reciprocal and Division of Fractions

Page 145: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

1225

*8

15 =

1225 5

3

2

3a. ÷

Reciprocal and Division of Fractions

Page 146: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a. ÷

Reciprocal and Division of Fractions

Page 147: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

÷

÷ =b.

Reciprocal and Division of Fractions

Page 148: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

÷

÷ = * b.

Reciprocal and Division of Fractions

Page 149: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

÷

÷ = * b.

Reciprocal and Division of Fractions

Page 150: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

Page 151: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

165d. ÷

Page 152: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

61*1

6 = 5d. ÷ 5

Page 153: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

61 = 30 *1

6 = 5d. ÷ 5

Page 154: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

61 = 30 *1

6 = 5d. ÷ 5

Example G. We have ¾ cups of sugar. A cookie recipe calls for 1/16 cup of sugar for each cookie. How many cookiescan we make?

Page 155: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

61 = 30 *1

6 = 5d. ÷ 5

Example G. We have ¾ cups of sugar. A cookie recipe calls for 1/16 cup of sugar for each cookie. How many cookiescan we make?

We can make 34 ÷ 1

16

Page 156: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

61 = 30 *1

6 = 5d. ÷ 5

Example G. We have ¾ cups of sugar. A cookie recipe calls for 1/16 cup of sugar for each cookie. How many cookiescan we make?

We can make 34 ÷ 1

16 = 34 *

161

Page 157: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

61 = 30 *1

6 = 5d. ÷ 5

Example G. We have ¾ cups of sugar. A cookie recipe calls for 1/16 cup of sugar for each cookie. How many cookiescan we make?

We can make 34 ÷ 1

16 = 34 *

161

4

Page 158: 13 fractions, multiplication and divisin of fractions

Example F. Divide the following fractions.

158

= 1225

*8

15 =

1225 5

3

2

3 910

a.

698

198 6

3

2

316

÷

÷ = * = b.

Reciprocal and Division of Fractions

61 = 30 *1

6 = 5d. ÷ 5

Example G. We have ¾ cups of sugar. A cookie recipe calls for 1/16 cup of sugar for each cookie. How many cookiescan we make?

We can make 34 ÷ 1

16 = 34 *

161 = 3 * 4 = 12 cookies.

4

HW: Do the web homework "Multiplication of Fractions"

Page 159: 13 fractions, multiplication and divisin of fractions

Multiplication and Division of Fractions

Remember to cancel first!

Page 160: 13 fractions, multiplication and divisin of fractions

Multiplication and Division of FractionsExercise. B. 12. In a class of 48 people, 1/3 of them are boys, how many girls are there?13. In a class of 60 people, 3/4 of them are not boys, how many boys are there?14. In a class of 72 people, 5/6 of them are not girls, how many boys are there?15. In a class of 56 people, 3/7 of them are not boys, how many girls are there?16. In a class of 60 people, 1/3 of them are girls, how many are not girls?17. In a class of 60 people, 2/5 of them are not girls, how are not boys?18. In a class of 108 people, 5/9 of them are girls, how many are not boys?A mixed bag of candies has 72 pieces of colored candies, 1/8 of them are red, 1/3 of them are green, ½ of them are blue and the rest are yellow.19. How many green ones are there?20. How many are blue?21. How many are not yellow?20. How many are not blue and not green? 21. In a group of 108 people, 4/9 of them adults (aged 18 or over), 1/3 of them are teens (aged from 12 to 17) and the rest are children. Of the adults 2/3 are females, 3/4 of the teens are males and 1/2 of the children are girls. Complete the following table.22. How many females are there and what is the fraction of the females to entire group?23. How many are not male–adults and what is the fraction of them to entire group?

Page 161: 13 fractions, multiplication and divisin of fractions

Improper Fractions and Mixed Numbers

B. Convert the following improper fractions into mixed numbers then convert the mixed numbers back to the improper form.

9 2

11 3

9 4

13 5

37 12

86 11

121 17

1. 2. 3. 4. 5. 6. 7.

Exercise. A. Reduce the following fractions.46 ,

812 ,

159 ,

2418 ,

3042 ,

5436 ,

6048 ,

72108