Skip to content
Auralith
Menu
Log inGet started

Year 7 · Maths · Primes, factors and probability · Lesson 1

Factors, multiples and primes

Find factors using factor pairs, list multiples, and identify prime numbers.

Whiteboard video lesson: Factors, multiples and primes

23-minute video lesson

Teaching, worked examples and 20 practice questions solved step by step.

Watch free for a month

What your child will learn

  • Understand factors and multiples
  • Find all factors using pairs
  • List multiples
  • Identify prime numbers
  • Solve problems with factors and multiples

The method

  1. Factors: find pairs, starting at 1.
  2. Stop when the pairs meet.
  3. Multiples: the times table.
  4. Prime: exactly 2 factors; 1 is not prime.

Key words: factor, multiple, prime, factor pair, divisible.

Worked examples

The first three practice questions from the lesson, with every step.

Question 1

List all the factors of 18.

  1. Step 1: Find factor pairs: 1 × 18, 2 × 9, 3 × 6
  2. Step 2: Stop when the pairs meet.
  3. Step 3: 1, 2, 3, 6, 9, 18

Answer: 1, 2, 3, 6, 9, 18

Question 2

List all the factors of 20.

  1. Step 1: Find factor pairs: 1 × 20, 2 × 10, 4 × 5
  2. Step 2: Stop when the pairs meet.
  3. Step 3: 1, 2, 4, 5, 10, 20

Answer: 1, 2, 4, 5, 10, 20

Question 3

List all the factors of 36.

  1. Step 1: Find factor pairs: 1 × 36, 2 × 18, 3 × 12, 4 × 9, 6 × 6
  2. Step 2: Stop when the pairs meet.
  3. Step 3: 1, 2, 3, 4, 6, 9, 12, 18, 36

Answer: 1, 2, 3, 4, 6, 9, 12, 18, 36