Prime numbers exercises 11 plus
21 October 2026
Understanding prime numbers
Prime numbers are whole numbers greater than 1 that can only be divided exactly by 1 and themselves. They have just two factors. For example, 2, 3, 5 and 7 are all prime numbers.
In the 11+ exam, children are often asked to spot prime numbers, list them, or use them to solve problems. Knowing how to identify primes is a key skill.
Why prime numbers matter for 11+
Questions about prime numbers can appear in different forms. Your child might need to recognise a prime number in a list, find all the primes between two numbers, or use prime numbers in factorisation problems.
Practising these skills helps build confidence for the test.
Worked example: Is 29 a prime number
Step 1: Check if 29 is greater than 1. Yes, it is.
Step 2: Try dividing 29 by 2. 29 ÷ 2 = 14.5, not a whole number.
Step 3: Try dividing by 3. 29 ÷ 3 = 9.666.., not a whole number.
Step 4: Try dividing by 5. 29 ÷ 5 = 5.8, not a whole number.
Step 5: Try dividing by numbers up to the square root of 29 (about 5.4). None divide exactly.
The correct answer is 29 is a prime number.
Practising prime number spotting
Ask your child to look at a list of numbers and pick out the primes. For example: 12, 13, 14, 15, 16, 17. The prime numbers here are 13 and 17.
Encourage your child to explain why each number is or is not a prime.
Key insight: Regular practice with prime numbers helps children recognise patterns, avoid common mistakes, and feel more confident when these questions appear in the 11+ exam.
