Go through the Math in Focus Grade 3 Workbook Answer Key Chapter 2 Practice 5 Using Front-End Estimation to finish your assignments.

## Math in Focus Grade 3 Chapter 2 Practice 5 Answer Key Using Front-End Estimation

**Write the leading digit.**

Question 1.

473 ___

Answer:

The leading digit is 4.

Question 2.

801 ___

Answer:

The leading digit is 8.

Question 3.

198 ____

Answer:

The leading digit is 1.

Question 4.

5,147 ___

Answer:

The leading digit is 5.

Question 5.

7,061 ___

Answer:

The leading digit is 7.

Question 6.

9,625 ____

Answer:

The leading digit is 9.

**Find the sum. Use front-end estimation to check that each answer is reasonable.**

Example

Question 7.

Find 312 + 526.

The estimated sum is ___

The answer ___ is reasonable.

Answer:

The estimated sum is 800

The answer is 838 is reasonable

**Find the sum. Use front-end estimation to check that each answer is reasonable.**

Question 8.

Find 364 + 509.

The estimated sum is ___

The answer ___ is reasonable.

Answer:

The estimated sum is 900

The answer 873 is reasonable.

Question 9.

Find 286 + 473.

The estimated sum is ___

The answer ___ is reasonable.

Answer:

The estimated sum is 800

The answer 759 is reasonable.

**Find the difference. Use front-end estimation to check that each answer is reasonable.**

Example

Question 10.

Find 618 – 372.

The estimated difference is ___

The answer ___ is reasonable.

Answer:

The estimated difference is 200

The answer 246 is reasonable.

Question 11.

Find 936 – 528.

The estimated difference is ___

The answer ___ is reasonable.

Answer:

The estimated difference is 400

The answer 408 is reasonable.

Question 12.

Find 759 – 236.

The estimated difference is ___

The answer ___ is reasonable.

Answer:

The estimated difference is 600

The answer 523 is not reasonable.

**Solve.**

Question 13.

The length of a train engine is 439 centimeters. The length of the carriage is about 558 centimeters. Estimate the total length of the train and the carriage.

Answer:

Given,

The length of a train engine is 439 centimeters. The length of the carriage is about 558 centimeters.

439 is near to 400 and 558 is near to 600.

So, 400 + 600 = 1000

Therefore, the Estimation of the total length of the train and the carriage is 1000 centimeters.

Question 14.

A wooden pole is 356 centimeters long. 104 centimeters of it is driven into the ground. About what height of the wooden pole is above the ground?

Answer:

Given,

A wooden pole is 356 centimeters long. 104 centimeters of it is driven into the ground.

356 is near to 400 and 104 is near to 100

So, 400 – 100 = 300

Therefore, approximately 300 centimeters of the wooden pole is above ground.