Check with the Opposite
Solve. Then check with the opposite. The check answer should match the top number.
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This is sheet #73724601.
How to do it
- Solve the problem on the left.
- Write the check problem on the right using your answer.
- The check should give you the top number.
Teaching tip
Checking with the opposite is a habit that catches lots of small mistakes. This sheet is aligned with Common Core 3.NBT.A.2.
About this worksheet
Solve each problem, then check it with the opposite. Add to check subtraction and subtract to check addition.
What kids practice
Third graders add and subtract within 1,000, working toward doing it smoothly and accurately. They regroup in more than one column, like 476 + 358, and subtract from numbers with zeros, like 400 − 126. They also use mental strategies, estimate with rounding, and check subtraction with addition.
Watch for
- Forgetting to add the carried 1.
- Subtracting the smaller digit from the bigger one in each column, no matter which is on top.
- Regrouping across a zero but forgetting to change the zero to 9.
It's free to print, with Fewer, Standard or More on the page and an answer key. See the full three-digit addition and subtraction guide for 3rd grade.
More sheets in this set
- See it all
1. Adding and Subtracting Strategies ChartThree ways to add and subtract within 1,000, stacking with regrouping, counting up on a number line and breaking apart by place. 
2. Add with Regrouping TwiceThree-digit addition where both the ones and the tens carry, like 476 + 358.
3. Subtract with Regrouping TwiceThree-digit subtraction where both the ones and the tens need to regroup, like 523 − 268.
4. Subtract Across ZerosSubtracting from numbers with zeros, like 400 − 126 and 503 − 247.
5. Add or Subtract? (Mixed)Three-digit addition and subtraction mixed on one page.
6. Estimate, Then SolveEstimate each problem by rounding to the nearest hundred, then solve it exactly on graph paper.