Using inverse operations to check answers
21 October 2026
What are inverse operations
Inverse operations are pairs of maths actions that undo each other. For example, addition and subtraction are opposites, as are multiplication and division. They are a key tool for checking answers in 11+ maths.
Why use inverse operations for checking
When your child solves a problem, using the inverse operation helps confirm the answer is correct. This method is quick and reduces careless mistakes.
Worked example
Suppose the question is 15 + 27 = 42.
To check, use subtraction: 42 - 27 = 15.
The result matches the original number, so the answer is correct.
Step-by-step checking
First, solve the original problem. Next, take your answer and apply the inverse operation. If you end up with the number you started with, the answer is likely right.
Summary of benefits
Checking with inverse operations builds confidence and catches errors early. It encourages careful, independent working for 11+ preparation.
Key insight: Encourage your child to check their work using the inverse operation every time. This habit makes mistakes less likely and helps them spot slips before moving on.
