3-5 Dividing Decimals by Whole Numbers

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3-5 Dividing Decimals by Whole Numbers

Learn to divide decimals by whole numbers.

3-5 Dividing Decimals by Whole Numbers

Divisor

Quotient

Remember!

0.150.755

Dividend

3-5 Dividing Decimals by Whole Numbers

Additional Example 1A: Dividing a Decimal by a Whole Number

Find the quotient.

0.84 ÷ 3

3 0.84

– 624

– 240

Place a decimal point in the quotient directly above the decimal point in the dividend. Divide as you would with whole numbers.

0.28

3-5 Dividing Decimals by Whole Numbers

Additional Example 1B: Dividing a Decimal by a Whole Number

Find the quotient.

3.56 ÷ 4

4 3.56

– 3236

– 360

Place a decimal point in the quotient directly above the decimal point in the dividend. Divide as you would with whole numbers.

0.89

3-5 Dividing Decimals by Whole Numbers

Check It Out: Example 1A

Find the quotient.

0.72 ÷ 3

3 0.72

– 612

– 120

Place a decimal point in the quotient directly above the decimal point in the dividend. Divide as you would with whole numbers.

0.24

3-5 Dividing Decimals by Whole Numbers

Check It Out: Example 1B

Find the quotient.

2.96 ÷ 4

4 2.96

– 2816

– 160

Place a decimal point in the quotient directly above the decimal point in the dividend. Divide as you would with whole numbers.

0.74

3-5 Dividing Decimals by Whole Numbers

Additional Example 2A: Evaluating Decimal Expressions

Evaluate 0.936 ÷ x for the given value of x.

x = 9

9 0.936– 9

3– 0

36

Substitute 9 for x. 0.10

0.936 ÷ x

0.936 ÷ 9

– 360

4Sometimes you need to use a zero as a placeholder.

9 > 3, so place a zero in the quotient and divide 9 into 36.

3-5 Dividing Decimals by Whole Numbers

Additional Example 2B: Evaluating Decimal Expressions

Evaluate 0.936 ÷ x for the given value of x.

x = 18

18 0.936– 0

93– 90

36

Substitute 18 for x. 0.05

0.936 ÷ x

0.936 ÷ 18

– 360

2Sometimes you need to use a zero as a placeholder.

18 > 9, so place a zero in the quotient and divide 18 into 93.

3-5 Dividing Decimals by Whole Numbers

Check It Out: Example 2A

Evaluate 0.636 ÷ x for the given value of x.

x = 6

6 0.636– 6

3– 0

36

Substitute 6 for x. 0.10

0.636 ÷ x

0.636 ÷ 6

– 360

6Sometimes you need to use a zero as a placeholder.

6 > 3, so place a zero in the quotient and divide 6 into 36.

3-5 Dividing Decimals by Whole Numbers

Check It Out: Example 2B

Evaluate 0.636 ÷ x for the given value of x.

x = 12

12 0.636– 0

63– 60

36

Substitute 12 for x. 0.05

0.636 ÷ x

0.636 ÷ 12

– 360

3Sometimes you need to use a zero as a placeholder.

12 > 6, so place a zero in the quotient and divide 12 into 63.

3-5 Dividing Decimals by Whole Numbers

Multiplication can “undo” division. To check your answer to a division problem, multiply the divisor by the quotient.

Remember!

3-5 Dividing Decimals by Whole Numbers

Additional Example 3: Consumer Application Jodi and three of her friends are making a tile design. The materials cost $10.12. If they share the cost equally, how much should each person pay?

4 $10.12– 8

21– 20

12

$2.53

$10.12 should be divided into four equal groups.

Divide $10.12 by 4.

– 120

Place a decimal point in the quotient directly above the decimal point in the dividend. Divide as you would with whole numbers.

Check2.53 4 = 10.12Each person should pay $2.53.

3-5 Dividing Decimals by Whole Numbers

Check It Out: Example 3

Ty and three of his friends are building a fence. The lumber costs $21.44. If they share the cost equally, how much should each person pay?

4 $21.44– 20

14– 12

24

$5.36

$21.44 should be divided into four equal groups.

Divide $21.44 by 4.

– 240

Place a decimal point in the quotient directly above the decimal point in the dividend. Divide as you would with whole numbers.

Check5.36 4 = 21.44Each person should pay $5.36.

3-5 Dividing Decimals by Whole Numbers

Check For Understanding

Find each quotient.

1. 3.12 ÷ 8 2. 5.68 ÷ 8

Evaluate the expression 1.25 ÷ x for the given

value of x.

3. x = 5 4. x = 25

5. The tennis team is having 3 of their tennis

rackets restrung. The total cost is $54.75. What is

the average cost per racket?