🔢 Mathematics · Addition & Subtraction

Inverse: addition undoes subtraction

Recognise and use the inverse relationship between addition and subtraction to check calculations and solve missing-number problems

Typical age: 6–7 years

“If your child works out 13 + 5 = 18, can they immediately use that to say '18 − 5 = 13' — without having to work the subtraction out all over again?”

0 / 3 mastered

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Needs first

Finding a missing number in additionREQUIRED
Inverse relationship builds on understanding subtraction as unknown-addend

Unlocks next

Unknown in Addition & Subtraction
Solving missing-number problems benefits from knowing the inverse relationship
Connecting Representations
Inverse relationship understanding requires moving between addition and subtraction representations
Estimating by roundingREQUIRED
Using inverse to check answers requires understanding the inverse relationship