3rd Grade Estimate Sums and Differences worksheets

About this worksheet

Estimating a sum or difference means rounding each number first and then computing with the rounded values, so the goal shifts from an exact answer to a reasonable one found quickly. Third graders often skip the rounding step and estimate by guessing, or they round only one of the two numbers and leave the other exact, which throws the estimate off. This worksheet always names the place to round to, either the nearest ten or the nearest hundred, and asks your child to round first and add or subtract the rounded numbers, choose the most reasonable estimate among several options, pick the correctly rounded pair of numbers, and solve short word problems that ask about how many rather than for an exact count.

Support versions round two-digit numbers to the nearest ten. Standard versions mix tens and hundreds. Challenge versions round three-digit numbers to the nearest hundred. Encourage your child to round every number in the problem before doing any adding or subtracting, and to check that an estimate is close to what the exact answer should be, not just any nearby number.

What your child will learn

• Round numbers to the nearest ten or hundred before estimating
• Add or subtract rounded numbers to estimate a sum or difference
• Choose the most reasonable estimate for a problem
• Solve word problems that ask about how many, using estimation