dividing by whole numbers lesson 2-4. in long division, we use both multiplication and division
TRANSCRIPT
Dividing by Whole Numbers
Lesson 2-4
In long division, we use both multiplication and division.
Key Vocabulary…
) dividenddivisor
quotient
Parts of a division problem…
GOES INTO
DIVIDED
BY
dividend
divisor= quotient
Parts of a division problem…
dividend ÷ divisor = quotient
factor x factor = product
Parts of a multiplication problem…
To keep your long division steps in order,
remember the basic family…• DAD
– Divide the divisor into the dividend• MOM
– Multiply the divisor by the factor you are about to put into your quotient
• SISTER– Subtract the product from the
dividend/difference• BROTHER
– Bring down the next digit in your problem• And the CAT
– Compare your new difference with the divisor to make sure it is smaller
• If the difference is larger than the divisor, then increase the last digit in your quotient by one.
36 ÷ 9369
Different Ways to Present the Same Problem
36 divided by 9
9 ) 36
9 divided into 36
“Divided by” means that the first number is the dividend and
the second number is the divisor.
“Divided into” means that the first number is the divisor and the second number is the
dividend.
Writing the Division Problem…
When you are thinking about lunch… I mean long division… think of In-and-Out.
Setting up your long division problem…
) 24
24 ÷ 9
9
IN – n- OUT
INOUT
) 249Does 9 go into 24?
Yes. 2 times. Put the 2 over the 4 (my last
underlined number)
29 x 2 = 18Subtract
24-18
-186
) 2492
-186
We do not leave remainders when we divide anymore. Now you need to add a decimal point to the end of the
dividend and add a zero.
.0
0
Bring the decimal point up into your
answer.
) 2492
-186
.0
0Does 9 go into 60?
How many times?
9 x 6 = 546
9 x 6 = 54
-5460 – 54 = 66
) 2492
-186
.0
0
6
-546
0
-540
6
6
Repeat the same steps…
) 2492
-186
.0
0
6
-546
0
-540
6
6
I see that if I go one more place, I will add another 6 to my quotient.
Do you see this repeating pattern?
) 2492.0606
I can see that the six will keep repeating itself. I am, therefore, going to round my answer to the hundredths place…
2.666 = 2.67
66666
How do I know where to round my answer to?
• If you are doing a problem from the book or on a test then read the directions for the answer to that question.
• If you are in a grocery store trying to figure out something that will cost money, round to the pennies place. (hundredths)
• If you see “round to the nearest whole number” or “round to the nearest dollar,” then round to the ones place.
• If your answer stops in the thousandths place, do not round your answer. Leave it as it is!
What do I do if I have zeroes in my problem?
) 1402.527Does 7 go into 14?
Yes. 2 times. Put the 2 over the 4 (my last
underlined number)
2 7 x 2 = 14
-140
Subtract 14-14= 0
) 1402.527Does 7 go into 0 or
00?
No. Put the 0 in the quotient over the 0 in the dividend.
2 7 x 0 = 0
-140 Bring
down the zero
0
0
00
0 – 0 = 0
) 1402.527
Does 7 go into 2?
No. Put the 0 in the quotient
over the 2.
2 7 x 0 = 0
-140 Bring
down the 20
0
002
0
2 – 0 = 2
02
) 1402.5272
-1400
0
002
0
0 2
Send up the
decimal point.
) 1402.527
Yes. 7 x 3 = 21. Put the 3 in the
quotient over the 5.
27 x 3 = 21
-140
Bring down the 5
0
0
002
0
25 – 21 = 4
0 2
Does 7 go into 25?
521
4
3
) 1402.527
Yes. 7 x 6 = 42. Put the 6 in the
quotient over the 2.
27 x 6 = 42
-140
Bring down the 2
0
0
002
0
42 – 42 = 0
0 25
Does 7 go into 42? 2
42
4
63
21 0
) 1402.527200 63
And the answer is…
Let’s Practice…
) 12.90634.302
) 5185103.6
) 108.54618.09
) 1661.8811151.08
) 1370.6222262.301