Solving Missing Number Calculations for 11+ Maths
21 October 2026
Solving missing number calculations
Missing number calculations are a key part of the 11+ Maths exam. These questions ask your child to find an unknown value in a sum or equation. Practising this skill helps children build strong problem-solving abilities.
Why this skill matters
Understanding how to find a missing number shows a child's grasp of number relationships and operations. It also prepares them for more advanced topics like algebra.
Worked example
7 +? = 12
First, set up the calculation as shown above. The goal is to find the value of the missing number, shown here as a question mark.
Step 1: Identify the operation
In this case, we are adding 7 to an unknown number to make 12. To find the missing number, we need to do the opposite of addition.
Step 2: Use the inverse operation
The inverse of addition is subtraction. So, subtract 7 from 12.
12 - 7 = 5
Step 3: Write the answer
The missing number is 5. The completed calculation is 7 + 5 = 12.
How parents can help
Encourage your child to practise similar questions. Remind them to use the inverse operation when they see a missing number. Regular practice builds confidence and accuracy.
Key insight: Mastering missing number calculations strengthens children's confidence and problem-solving skills for the 11+ exam.
