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Chapter 3

Decimals

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Section 3.4

Dividing Decimals

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Divide a Decimal by a Whole Number

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Example

Divide.

a.

b. 124.18 ÷ 4

c. 0.24 ÷ 3

6 14.28

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Solution Strategy

a. 6 14.28−12

22−18

48−48

0

2.384 124.18

−124

−418

−1620

−200

31.045b. 3 0.24

−240

.08c.

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Divide a Decimal by a Power of 10

Dividing a Decimal by a Power of 10 such as 10, 100, 1000 . . .

Move the decimal point in the dividend to the left the same number of places as there are zeros in the power of 10. Insert zeros, as necessary.

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Divide a Decimal by a Power of 10

Dividing a Decimal by a Power of 10 such as 0.1, 0.01, 0.001 . . .

Move the decimal point in the dividend to the right the same number of places as there are place values in the decimal power of 10. Insert zeros as necessary.

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Example

d. 13,000 ÷ 0.001

Divide.

b. 58.73 ÷ 1000

c.

100 15.306a.

3.724

0.01

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Solution Strategy

= 0.15306

= 0.05873

= 372.4

= 13,000,000d. 13,000 ÷ 0.001

Divide.

b. 58.73 ÷ 1000

100 15.306

3.724

0.01c.

a.

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Divide a Decimal or a Whole Number by a Decimal

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Example

Divide.

b.

c.

0.59 32.686a.

1.4 17.675

6.4 34.24 Round to the nearest tenth.

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Solution StrategyDivide.

a.

b. 14 176.750−14

36−28

87−84

35−28

70−70

0

12.625

59 3268.6−295

318−295

236−236

0

55.45.4c.

64 342.40−320

224−192

320−320

0

5.35

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Estimate When Dividing Decimals

Steps for Estimating Dividing Decimals

Step 1. Round each number to the specified place.

Step 2. Divide the rounded dividend by the rounded divisor.

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Example

Divide 86.7 ÷ 8.5

Then estimate the quotient by rounding the dividend and divisor to one nonzero digit.

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Solution Strategy

Then estimate the quotient by rounding the dividend and divisor to one nonzero digit.

85 867.0−85

170−170

0

10.2

10 100−100

0

10

Divide 86.7 ÷ 8.5

86.7 ÷ 8.5

100 ÷ 10

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Calculating an Average

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Example Apply your knowledge

You are a clerk at The Time and Again boutique. This morning you made sales of $213.37, $143.77, and $89.62. What is the average of your morning sales?

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Solution Strategy

= $148.92213.37 +143.77 + 89.62

3=

446.763

You are a clerk at The Time and Again boutique. This morning you made sales of $213.37, $143.77, and $89.62. What is the average of your morning sales?