© t madas. sometimes we have to round numbers what does rounding mean? can you think of some...

© T Madas

Sometimes we have to round numbers

What does rounding mean?

Can you think of some examples?

© T Madas

4040

Rounding to the nearest 10

The rounded number must have a zero at the end

Round 37 to the nearest 10

30 37

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The rounded number must have a zero at the end


160150 154150

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130120 125 130

When our number lies halfway between “tens”, we have agreed to round the number up.

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Rounding to the nearest 10Numbers ending in 1, 2, 3 and

4 get rounded downNumbers ending in 5, 6, 7 , 8 and 9 get rounded up

Examples:

27 30

94 90

146 150

305 310

68 70

132 130

565 570

481 480

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800800


The rounded number must have 2 zeros at the end


700 764

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12001200



13001235


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900900


800 850

When our number lies halfway between “hundreds”, we have agreed to round the number up.


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Numbers ending in 0s, 10s, 20s, 30s and 40s get rounded downNumbers ending in 50s, 60s, 70s , 80s and 90s get rounded up

Examples:

237 200

874 900

536 500

350 400

1168 1200

2032 2000

5750 5800

40081 40100


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80008000




7000 7761

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80008000



90008339


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70007000


6000 6500

When our number lies halfway between “thousands”, we have agreed to round the number up.


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Numbers ending in 00s, 100s, 200s, 300s and 400s get rounded downNumbers ending in 500s, 600s, 700s , 800s and 900s get rounded up

Examples:

2837 3000

4874 5000

5376 5000

7500 8000

1868 2000

2499 2000

29780 30000

45681 46000


© T Madas

Practice Roundingto the nearest…

© T Madas

Round these numbers to the nearest…

48

87

184

145

1563

3217

2005

50

90

180

150

1560

3220

2010

…10

209

2867

3467

1095

1550

45678

61981

200

2900

3500

1100

1600

45700

62000

…100

3456

5349

89231

37849

32489

49838

71974

3000

5000

89000

38000

32000

50000

72000

…1000

…whole number2.7

4.2

10.4

3

4

10

27.9

7.67

33.37

28

8

33

31.436

764.92

0.86

31

765

1

© T Madas


78

67

181

125

1343

3787

1998

80

70

180

130

1340

3790

2000

…10

279

2557

23107

16915

1850

49805

61041

300

2600

23100

16900

1900

49800

61000

…100

76532

64543

37859

90832

98114

89575

70456

77000

65000

38000

91000

98000

90000

70000

…1000

…whole number2.8

8.2

11.4

3

8

11

37.9

7.17

39.67

38

7

40

37.685

344.02

0.81

38

344

1

© T Madas

Quick Teston Roundingto the nearest…

© T Madas


48

87

184

145

1563

3217

2005

50

90

180

150

1560

3220

2010

…10

209

2867

3467

1095

1550

45678

61981

200

2900

3500

1100

1600

45700

62000

…100

3456

5349

89231

37849

32489

49838

71974

3000

5000

89000

38000

32000

50000

72000

…1000

…whole number2.7

4.2

10.4

3

4

10

27.9

7.67

33.37

28

8

33

31.436

764.92

0.86

31

765

1

© T Madas


78

67

181

125

1343

3787

1998

80

70

180

130

1340

3790

2000

…10

279

2557

23107

16915

1850

49805

61041

300

2600

23100

16900

1900

49800

61000

…100

76532

64543

37859

90832

98114

89575

70456

77000

65000

38000

91000

98000

90000

70000

…1000

…whole number2.8

8.2

11.4

3

8

11

37.9

7.17

39.67

38

7

40

37.685

344.02

0.81

38

344

1

© T Madas

We look at the 1st decimal place• If it is 0, 1, 2, 3 or 4 we just throw all the

decimal digits away

• If it is 5, 6, 7, 8 or 9 we throw all the decimal digits away and we increase the units by 1

Rounding decimals… to the nearest whole number

Examples:

23.7 24

8.94 9

53.6 54

3.52 4

1.768 2

20.32 20

5.8757 6

40.071 40

© T Madas

We look at the 2nd decimal place• If it is 0, 1, 2, 3 or 4 we just throw the 2nd, the

3rd, the 4th … decimal digits away

• If it is 5, 6, 7, 8 or 9 we throw the 2nd, the 3rd, the 4th … decimal digits away and we increase the 1st decimal digit by 1

Rounding decimals… to one decimal place

Examples:

3.734 3.7

8.294 8.3

9.16 9.2

6.52 6.5

5.728 5.7

41.32 41.3

5.8757 5.9

40.071 40.1

© T Madas

We look at the 3rd decimal place• If it is 0, 1, 2, 3 or 4 we just throw the 3rd, the

4th, the 5th … decimal digits away

• If it is 5, 6, 7, 8 or 9 we throw, the 3rd, the 4th, the 5th … decimal digits away and we increase the 2nd decimal digit by 1

Rounding decimals… to two decimal places

Examples:

3.7342 3.73

5.2863 5.29

0.1605 0.16

2.5782 2.58

5.7028 5.70

4.3592 4.36

5.8957 5.90

4.9971 5.00

© T Madas

0.49978

8.5328

3.5004

4.089623

6.40078

5.36581

0.10704

1.48173

2.2258

9.2341

Round the following numbers to 1 decimal places

0.49878

7.3058

2.585423

0.46878

2.3553

9.48973

1.3173

8.75438

4.6751

1.56437

6.39745

5.471

3.117

1.8671.9

5.5

0.43456

6.4

5.245567

0.9034

1.6

4.7

8.8

2.724

1.32

9.49

4.1424

2.36

0.47

3.5024

2.59

7.31

0.50

2.226

1.482

5.366

6.401

4.090

8.533

0.500

23

© T Madas

5.36581

0.10704

1.48173

2.2258

9.2341

Round the following numbers to decimal places

2.3553

9.48973

1.3173

6.39745

5.471

3.117

1.8671.9

5.5

0.43456

6.4

2.724

1.32

9.49

4.1424

2.36

2.226

1.482

5.366

1 d.p. 2 d.p. 3 d.p.

© T Madas

Round the following numbers to decimal places

1 d.p. 2 d.p. 3 d.p.

0.49978

8.5328

3.5004

4.089623

6.40078

0.49878

7.3058

2.585423

0.46878

8.75438

4.6751

1.56437

5.245567

0.9034

1.6

4.7

8.8

0.47

3.5024

2.59

7.31

0.50

6.401

4.090

8.533

0.500

© t madas. sometimes we have to round numbers what does rounding mean? can you think of some...

Documents

nearest slide

t madas slide

t madas numbers

t madas practice

rounded number

end round

t madas quick test