Practice the problems of Math in Focus Grade 5 Workbook Answer Key Chapter 9 Practice 5 Estimating Decimals to score better marks in the exam.

## Math in Focus Grade 5 Chapter 9 Practice 5 Answer Key Estimating Decimals

**Round each decimal to the nearest whole number. Then estimate the sum or difference.**

Example

7.7 + 12.3

7.7 rounds to 8.

12.3 rounds to 12.

8 + 12 = 20

7.7 + 12.3 is about 20.

21.8 – 11.5

21.8’ rounds to 22.

11.5 rounds to 12.

22 – 12 = 10

21.8 – 11.5 is about 10.

Question 1.

$2.90 + $7.15

Answer: $10.05

Estimate: 10

Explanation:

2.90 + 7.15

2.90 rounds to 3.

7.15 rounds to 7.

3 + 17 = 10

2.90 + 7.15 is about 10.

Question 2.

9.05 + 19.55

Answer: $28.6

Estimate: 29

Explanation:

9.05 + 19.55

9.05 rounds to 9.

19.55 rounds to 20.

9 + 20 = 29

9.05 + 19.55 is about 29.

Question 3.

35.67 – 15.09

Answer: $20.58

Estimate: 21

Explanation:

35.67 – 15.09

35.67 rounds to 36.

15.09 rounds to 15.

36 – 15 = 21

35.67 – 15.09 is about 21.

Question 4.

$15.40 – $5.95

Answer: $9.45

Estimate: 9

Explanation:

15.40 – 5.95

15.40 rounds to 15.

5.95 rounds to 6.

15 – 6 = 9

15.40 – 5.95 is about 9.

**Estimate the product by rounding the decimal to the nearest whole number.**

Example

4.5 × 4

4.5 rounds to 5.

5 × 4 = 20

4.5 × 4 is about 20.

Question 5.

19.6 × 3

Answer: 58.8

Estimate: 60

Explanation:

19.6 × 3

19.6 rounds to 20.

20 × 3 = 60

19.6 × 3 is about 60.

Question 6.

0.95 × 8

Answer: 7.6

Estimate:800

Explanation:

0.95 × 8

0.95 rounds to 100.

100 x 8 = 800

0.95 × 8 is about 800.

Question 7.

8.25 × 3

Answer: 24.75

Estimate: 2400

Explanation:

8.25 × 3

8.25 rounds to 800.

800 × 3 = 2400

8.25 × 3 is about 2400.

**Estimate the quotient by choosing a whole number close to the dividend that can be evenly divided by the divisor.**

Example

24.6 ÷ 5

24.6 is about 25.

25 ÷ 5 = 5

24.6 ÷ 5 is about 5.

Question 8.

38.4 ÷ 6

Answer: 6.4

Estimate: 6

Explanation:

38.4 ÷ 6

38.4 is about 36.

36 ÷ 6 = 6

38.4 ÷ 6 is about 6.

Question 9.

71.09 ÷ 8

Answer: 8.8

Estimate: 9

Explanation:

71.09 ÷ 8

71.09 is about 72.

72 ÷ 8 = 9

71.09 ÷ 8 is about 9.

Question 10.

99.75 ÷ 5

Answer: 19.95

Estimate: 20

Explanation:

99.75 ÷ 5

99.75 is about 100.

100 ÷ 5 = 20

99.75 ÷ 5 is about 20.

**Round each decimal to the nearest tenth. Then estimate.**

Question 11.

0.47 + 15.51

Answer: 15.98

Estimate: 16

Explanation:

0.47 + 15.51

0.47 rounds to 1.

15.51 rounds to 15.

15 + 1 = 16

0.47 + 15.51 is about 16.

Question 12.

9.95 – 1.46

Answer: 8.49

Estimate: 9

Explanation:

9.95 – 1.46

9.95 rounds to 10.

1.46 rounds to 1.

10 – 1 = 9

9.95 – 1.46 is about 9.

Question 13.

2.89 pounds × 4

Answer: 11.56

Estimate: 1200

Explanation:

2.89 × 4

2.89 rounds to 300.

300 × 4 = 1200

2.89 × 4 is about 1200.

**Estimate the quotient by choosing a tenth close to the dividend that can be evenly divided by the divisor.**

Question 14.

6.34 kilograms ÷ 7

Answer: 0.90

Estimate: 1

Explanation:

6.34 ÷ 7

6.34 is about 7.

7 ÷ 7 = 1

6.34 ÷ 7 is about 1.

**Solve. Show your work.**

Question 15.

A bag of walnuts sells for $1.95. Estimate the cost of 8 bags of walnuts.

Answer: $15.6

Estimate: 16

Explanation:

1.95 × 8

1.95 rounds to 2.

2 × 8 = 16

1.95 × 8 is about 16.

Question 16.

A piece of plywood is 1 .27 centimeters thick. Find the thickness of a pile of 9 pieces of plywood to the nearest tenth of a centimeter. Estimate to check if your answer is reasonable.

Answer: 11.43 cm

Estimate: 1170

Explanation:

1.27 × 9

1.27 rounds to 130.

130 × 9 = 1170

1.27 × 9 is about 1170.