11+ Maths

Factors and Primes in the 11+ — Questions, Worked Answers and Practice Papers

Finding factors, multiples and prime numbers — foundational number facts for the 11+.

67 Papers
1.7 Avg Qs / paper
2.04 Typical marks
44 sec Target time

What examiners actually ask

Factors and Primes appears in 67 of our 338 ready papers (111 tagged questions). It averages 1.7 questions a paper worth about 2.04 marks each. The typical question allows around 44 sec. It appears in 3 CSSE papers we hold.

Factors and primes appear as quick number questions and as building blocks for fractions and sequences. Papers ask for factor pairs, common factors, multiples, and whether a number is prime. Children who list factors randomly miss pairs; children who think 1 is prime (or that all odd numbers are prime) lose easy marks. Teach systematic listing from 1 up to the square root, and memorise primes to at least 20. Link this practice to fraction simplification so the skill pays off elsewhere in the paper. Under time pressure, write factor pairs opposite each other so you can see immediately if a pair is missing before moving on.

Worked example

A real tagged question from our catalogue — method included, not paywalled.

Emanuel School 11+ Maths Test Paper · Question 32 c · 3 marks · Factors

Correct answer
Method

Common mistakes

  • Calling 1 a prime number.
  • Missing factor pairs by not listing systematically.
  • Confusing factors with multiples in the question wording.
  • Assuming every odd number is prime.

Papers with the most Factors and Primes questions

Ranked from our tagged catalogue — open a paper to practise the questions that actually test this topic.

Find what is actually costing marks

Not sure whether factors and primes is the problem? Mark any past paper on 11plusSolved and the report tells you which topics are costing marks — and how many.