Estimating Sums and Differences Worksheet

Question 1

Estimate 28 + 41 by rounding each number to the nearest ten.

Accepted Answer

28 rounds to 30 and 41 rounds to 40, so 28 + 41 is about 70.

Question 2

Estimate 64 - 29 by rounding each number to the nearest ten.

Accepted Answer

64 rounds to 60 and 29 rounds to 30, so 64 - 29 is about 30.

Question 3

Mia has 37 stickers. Her friend gives her 22 more stickers. About how many stickers does Mia have now? Round to the nearest ten.

Accepted Answer

37 rounds to 40 and 22 rounds to 20, so Mia has about 60 stickers now.

Question 4

Estimate 83 - 46 by rounding each number to the nearest ten.

Accepted Answer

83 rounds to 80 and 46 rounds to 50, so 83 - 46 is about 30.

Question 5

Estimate 19 + 52 by rounding each number to the nearest ten.

Accepted Answer

19 rounds to 20 and 52 rounds to 50, so 19 + 52 is about 70.

Question 6

A bus has 48 students on it. At the next stop, 31 more students get on. About how many students are on the bus? Round to the nearest ten.

Accepted Answer

48 rounds to 50 and 31 rounds to 30, so there are about 80 students on the bus.

Question 7

Estimate 72 + 18 by rounding each number to the nearest ten.

Accepted Answer

72 rounds to 70 and 18 rounds to 20, so 72 + 18 is about 90.

Question 8

Estimate 95 - 42 by rounding each number to the nearest ten.

Accepted Answer

95 rounds to 100 and 42 rounds to 40, so 95 - 42 is about 60.

Question 9

Liam read 56 pages of a book last week and 23 pages this week. About how many pages did Liam read in all? Round to the nearest ten.

Accepted Answer

56 rounds to 60 and 23 rounds to 20, so Liam read about 80 pages in all.

Question 10

Which is the better estimate for 44 + 27: 60 or 70? Explain your choice.

Accepted Answer

70 is the better estimate because 44 rounds to 40 and 27 rounds to 30, and 40 + 30 = 70.

Question 11

Estimate 68 - 21 by rounding each number to the nearest ten.

Accepted Answer

68 rounds to 70 and 21 rounds to 20, so 68 - 21 is about 50.

Question 12

A farmer picked 74 apples. She sold about 39 of them. About how many apples were left? Round to the nearest ten.

Accepted Answer

74 rounds to 70 and 39 rounds to 40, so about 30 apples were left.

Question 13

Estimate 36 + 58 by rounding each number to the nearest ten.

Accepted Answer

36 rounds to 40 and 58 rounds to 60, so 36 + 58 is about 100.

Question 14

The school library has 89 mystery books and 34 science books. About how many books is that altogether? Round to the nearest ten.

Accepted Answer

89 rounds to 90 and 34 rounds to 30, so there are about 120 books altogether.

Question 15

Nora estimated 53 - 18 as 50 - 20 = 30. Is her estimate reasonable? Explain.

Accepted Answer

Yes, her estimate is reasonable because 53 rounds to 50 and 18 rounds to 20, so the difference is about 30.

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