Addition and subtraction are related operations: in a fact such as , subtracting either addend from 12 recovers the other, so a subtraction fact can informally verify an addition result. This relationship is interpreted through part–whole representations, equations, or a number line with familiar whole numbers, primarily within 20; it does not include formal inverse-operation notation, larger-number algorithms, or generalized algebraic proofs.
When you add two parts to make a whole, you can check your answer by taking away one part from the whole. The part left should be the other addend.
Example: Check .
So, is correct.
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