Word problem: finding the missing number
22 October 2026
Word-based problems with missing numbers often appear in 11+ maths. These questions ask your child to find out what number is missing from a story or situation. It helps to break the problem into clear steps and use simple maths sentences.
Worked example
Sophie has some apples. She buys 7 more apples and now has 15 apples. How many apples did Sophie have at first?
Step 1: Write a number sentence for the problem.
Let the missing number be □.
□ + 7 = 15
Step 2: Work out how to find the missing number.
We need to find what plus 7 makes 15.
Step 3: Use the opposite operation (subtraction). 15 - 7 = 8
Step 4: Check your answer.
8 + 7 = 15. This is correct.
The correct answer is 8.
Click or tap on the number line to answer
Key insight: After working through this example, your child will see how to turn a word problem into a number sentence and use the opposite operation to find the answer. They can now try similar missing number questions with confidence.
