Skill: Check subtraction with addition

Explanation and Free Practice Resources

Subtraction and addition are inverse operations: for a subtraction equation $a-b=c$ , adding the difference $c$ to the subtrahend $b$ should reproduce the minuend $a$ . This relationship enables checking subtraction involving whole numbers within 1,000, including regrouping, and helps identify errors in place-value reasoning or computation while supporting later work with equations and unknown quantities.

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Detailed Explanation: Check subtraction with addition

To check a subtraction answer, add the difference to the number you subtracted. The sum should equal the original number.

For example:

542-278=264

Check the answer by adding $264$ and $278$ :

Ones: $4+8=12$ . Write $2$ ones and regroup $1$ ten.
Tens: $6+7+1=14$ . Write $4$ tens and regroup $1$ hundred.
Hundreds: $2+2+1=5$ .

So,

278+264=542

Because the sum is the original number, $542$ , the subtraction answer is correct:

\boxed{542-278=264}

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Subtraction - Missing Value, 3 Digit, 1 Number

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