Go through the Math in Focus Grade 4 Workbook Answer Key Chapter 3 Whole Number Multiplication and Division to finish your assignments.

## Math in Focus Grade 4 Chapter 3 Answer Key Whole Number Multiplication and Division

**Math Journal**

**Look at each problem. Use estimation to explain why the answers are not reasonable.**

Example

5,268 × 8 = 2,144

Explain.

__5,268 is about 5,000__

__5,000 × 8 = 40,000__

__So the answer is too small__.

Question 1.

725 × 6 = 700

Explain.

Answer:

725 is about 700

700 × 6 = 4,200

So the answer is too small.

Question 2.

497 × 21 = 1,291

Explain.

Answer:

497 is about 500

500×21 = 10,500.

So the answer is too small.

**Use estimation to explain why the answer is not reasonable.**

Question 3.

6,021 ÷ 3 = 207

Explain.

____

Answer:

6,021 is about 6,000

6,000 ÷ 3 = 2,000.

So the answer is too small.

**Solve. Show your work.**

Question 4.

Look at the number sentence.

72 ÷ 6 = 12

How would you use this to find the missing quotient?

7200 ÷ 6 =

Answer:

7200 ÷ 6 = 1200.

Explanation:

As 72 ÷ 6 = 12, so for 7200 ÷ 6 it will be 1200.

**Put on Your Thinking cap!**

**Challenging Practice**

Charlie has 1,243 stamps. He gives away 12 stamps. His father gives him 415 stamps. He divides as many stamps as possible equally among 4 albums.

Question 1.

How many stamps did he place in each album?

Answer:

He places 411 stamps in each album.

Explanation:

Given that Charlie has 1,243 stamps and he gives away 12 stamps then it will be 1,243 – 12 = 1,231 and his father gives him 415 stamps then it will be 1,231+415 which is 1,646. As he divides as many stamps as possible equally among 4 albums it will be 1,646÷4 which will be approx 411 stamps.

Question 2.

Based on your answer in Exercise 1, how many stamps are left over?

Answer:

2 stamps.

Explanation:

The number of stamps leftover is 2 stamps.

**Put on Your Thinking Cap!**

**Problem Solving**

Question 1.

The cost of 2 televisions and 3 DVD players is $1,421. The cost of 1 DVD player is half the cost of 1 television. What is the cost of 1 television?

Answer:

Explanation:

Given that the cost of 2 televisions and 3 DVD players is $1,421 and the cost of 1 DVD player is half the cost of 1 television. Let the cost of 1 DVD player be X, so the price of the television will be 2X. So 2 televisions and 3 DVD player will be 2(2X)+3(X) = $1,421

4X+3X = $1,421

7X = $1,421

X = $203.

So the cost of 1 television it will be 2($203) which is $406.