Estimating with Compatible Numbers Worksheet

Question 1

Estimate 398 + 204 using compatible numbers. Explain which numbers you used.

Accepted Answer

398 is close to 400, and 204 is close to 200. So 398 + 204 is about 400 + 200 = 600.

Question 2

Maya has 487 stickers, and her friend gives her 312 more. Use compatible numbers to estimate how many stickers Maya has now.

Accepted Answer

487 is close to 500, and 312 is close to 300. Maya has about 500 + 300 = 800 stickers.

Question 3

Estimate 721 - 298 using compatible numbers. Show your thinking.

Accepted Answer

721 is close to 700, and 298 is close to 300. So 721 - 298 is about 700 - 300 = 400.

Question 4

A school library has 1,206 books. Students check out 398 books. Estimate how many books are left using compatible numbers.

Accepted Answer

1,206 is close to 1,200, and 398 is close to 400. There are about 1,200 - 400 = 800 books left.

Question 5

Estimate 49 x 21 using compatible numbers. Explain your estimate.

Accepted Answer

49 is close to 50, and 21 is close to 20. So 49 x 21 is about 50 x 20 = 1,000.

Question 6

A bus holds 38 students. About how many students can ride on 9 buses? Use compatible numbers.

Accepted Answer

38 is close to 40, and 9 is already easy to use. About 40 x 9 = 360 students can ride on 9 buses.

Question 7

Estimate 2,412 ÷ 6 using compatible numbers. Show how you chose your numbers.

Accepted Answer

2,412 is close to 2,400, and 2,400 divides evenly by 6. So 2,412 ÷ 6 is about 2,400 ÷ 6 = 400.

Question 8

A farmer packs 1,785 apples equally into 9 boxes. Estimate how many apples are in each box using compatible numbers.

Accepted Answer

1,785 is close to 1,800, and 1,800 divides evenly by 9. Each box has about 1,800 ÷ 9 = 200 apples.

Question 9

Choose the better compatible number estimate for 603 + 198: 600 + 200 or 500 + 100. Explain your choice.

Accepted Answer

600 + 200 is the better estimate because 603 is close to 600 and 198 is close to 200. The estimate is 800.

Question 10

Estimate 4,089 - 1,987 using compatible numbers.

Accepted Answer

4,089 is close to 4,100 or 4,000, and 1,987 is close to 2,000. One good estimate is 4,100 - 2,000 = 2,100.

Question 11

A theater sold 52 tickets for each of 18 shows. Estimate the total number of tickets sold using compatible numbers.

Accepted Answer

52 is close to 50, and 18 is close to 20. The theater sold about 50 x 20 = 1,000 tickets.

Question 12

A student estimates 3,152 ÷ 8 by using 3,200 ÷ 8. Is this a good compatible number estimate? Explain why or why not.

Accepted Answer

Yes, this is a good estimate because 3,200 is close to 3,152 and divides evenly by 8. The estimate is 3,200 ÷ 8 = 400.

Estimating with Compatible Numbers