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Estimating Differences Worksheets for 3rd Grade

Round each number first, then subtract to estimate a difference. 15 free printable worksheets, each with an answer key.

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Free Estimating Differences Worksheets

Click a worksheet to open the PDF, or grab the matching answer key. Every sheet prints on one page.

Estimating Differences: what children learn

To estimate a difference, children round both numbers to the named place and then subtract the rounded numbers. The estimate should land near the exact difference.

Estimating Differences: worked example

Round to the nearest 10. About how much is 83 - 38? 40

83 rounds to 80 and 38 rounds to 40. Then 80 - 40 = 40.

Estimating Differences: a common mistake to watch for

Kids often round only one of the two numbers, or round to the wrong place.

Estimating Differences: how to help at home or in class

Use a real book. Say it has 346 pages and your child has read 187, so about how many pages are left? Round to the nearest ten to get 350 and 190, subtract for an estimate of 160, then work out the exact difference of 159 and compare. Make estimating a habit before every subtraction. When the estimate and exact answer agree closely, skip counting patterns are a good change of pace.

What is on these Estimating Differences worksheets

This set has 15 different worksheets for 3rd grade, with 8 questions on each and a matching answer key for every sheet. The instruction printed on each worksheet is: “Round each number first. Then subtract the rounded numbers.”

Example questions like the ones on these worksheets, with their answers:

  • Round to the nearest 10. About how much is 56 - 19?40
  • Round to the nearest 10. About how much is 47 - 18?30
  • Round to the nearest 10. About how much is 53 - 12?40
  • Round to the nearest 10. About how much is 91 - 36?50
  • Round to the nearest 10. About how much is 79 - 36?40
  • Round to the nearest 10. About how much is 81 - 67?10
  • Round to the nearest 10. About how much is 93 - 12?80
  • Round to the nearest 10. About how much is 615 - 427?190

Every answer on every sheet is checked by a separate program before the worksheet is published. How we check answers

Related Place Value & Rounding worksheets for 3rd grade

Rounding to the Nearest 10
Round numbers up to 999 to the nearest ten, including numbers that end in 5.
Rounding to the Nearest 100
Round three-digit numbers to the nearest hundred, including numbers that end in 50.
Rounding to the Nearest 10 or 100
Round numbers to the nearest 10 or the nearest 100, as each question says.
Estimating Sums
Round each number first, then add to estimate a sum.
All Place Value & Rounding worksheets
See every place value & rounding topic for 3rd grade