Equations with Missing Numbers: A Parent's Guide for 11+ Maths
22 October 2026
Equations with missing numbers
Equations with missing numbers are questions where a value is hidden, often shown as a box or a letter. Your child's task is to work out what number completes the equation and makes both sides equal.
Why this matters for 11+ preparation
These questions appear regularly in 11+ exams. They check if children understand number relationships and can use logic to find unknown values. Practising these problems helps build algebra skills that are vital for secondary school.
How to solve missing number equations
The key is to spot what operation is being used and then use the inverse operation to find the missing number. For example, if the equation is 7 + □ = 12, your child should use subtraction to find the answer: 12 - 7.
Step-by-step approach
1. Read the equation carefully.
2. Identify the operation (add, subtract, multiply, divide).
3. Use the inverse operation to isolate the missing number.
4. Check the answer by substituting it back into the equation.
Key insight: Encourage your child to say what they are doing out loud. Talking through each step helps them spot mistakes and understand the logic behind each move.
Tips for parents
Start with simple examples and build up to more complex ones. Use objects or drawings if your child finds it easier to visualise the problem. Remind them that it's normal to try more than once and that checking their answer is part of good maths practice.
Worked example
4 × □ = 28
Start by identifying the operation: multiplication.
To find the missing number, use the inverse operation: division.
Divide 28 by 4.
28 ÷ 4 = 7
The correct answer is 7.
