← Back to the activity

Class 6 Maths — HCF and LCM

Find the highest common factor and the lowest common multiple of two numbers, and use them to answer sharing and repeating problems.

Name: ________________________

Before you start

Every mark here is a multiple of 4 and a multiple of 6 at the same time. Move from one to the next.

01224364860

Zero is a multiple of everything, so it never counts. The first mark after it is 12, and that is what the LCM of 4 and 6 means — the earliest place their two lists of multiples meet.

  1. 1.What is the LCM of 4 and 6?

  2. 2.Which pair of numbers has an HCF of 1?

    • a) 10 and 15
    • b) 8 and 15
    • c) 8 and 12
    • d) 9 and 15

  3. 3.One bell rings every 6 minutes and another rings every 8 minutes. They have just rung together. In how many minutes will they next ring together?

  4. 4.Which of these is 60 written as a product of prime factors?

    • a) 2 × 2 × 3 × 5
    • b) 2 × 3 × 10
    • c) 4 × 15
    • d) 2 × 5 × 6

  5. 5.Match each pair of numbers to their HCF.

    • 6 and 9
    • 8 and 12
    • 10 and 15
    • 14 and 21
    • 16 and 24
    • 3
    • 7
    • 4
    • 5
    • 8

  6. 6.What is the HCF of 7 and 13?

  7. 7.Work out the LCM of each pair, then sort by whether it is below 30 or above 30.

    Groups: LCM below 30 · LCM above 30

    • 5 and 8
    • 3 and 8
    • 4 and 6
    • 9 and 12
    • 7 and 10
    • 6 and 9

  8. 8.What is the LCM of 5 and 8?

Answer key — Class 6 Maths — HCF and LCM

  1. 1. 12
  2. 2. b) 8 and 15
  3. 3. 24
  4. 4. a) 2 × 2 × 3 × 5
  5. 5. 6 and 9 → 3; 8 and 12 → 4; 10 and 15 → 5; 14 and 21 → 7; 16 and 24 → 8
  6. 6. 1
  7. 7. 4 and 6 → LCM below 30; 3 and 8 → LCM below 30; 6 and 9 → LCM below 30; 5 and 8 → LCM above 30; 9 and 12 → LCM above 30; 7 and 10 → LCM above 30
  8. 8. 40