# Lowest common multiple and prime factors

## Lesson details

### Key learning points

1. In this lesson, we will use prime factorisation to identify common multiples and the lowest common multiple. We will also use Venn diagrams to sort prime factors.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

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## Worksheet

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## Starter quiz

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### 5 Questions

Q1.
Find the lowest common multiple of 3 and 6
18
2
3
Q2.
Find the highest common factors of 3 and 6
18
2
6
Q3.
Find the LCM of 14 and 21
2 and 3
21
294
7
Q4.
A pair of numbers have LCM OF 24. What could the pair of numbers be?
12 and 2
24 and 48
6 and 4
Q5.
Zaki says that 2 prime numbers LCM is found by multiplying the prime numbers together, Is this true or false?
False

## Exit quiz

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### 5 Questions

Q1.
Fill in the gaps, in the correct order: Writing numbers as a __________ of their _______ factors helps you to find the lowest common multiple.
product, common
subtraction, common
subtraction, prime
Q2.
The Venn diagram shows the prime factors of 60 and 84. Write 60 as a product of its prime factors.
Correct answer: 2 × 2 × 3 × 5
2 × 2 × 3 × 7
2 × 2 × 3 × 7 × 5
2, 2, 3, 5
Q3.
The Venn diagram shows the prime factors of 60 and 84. Write 84 as a product of its prime factors.
2 × 2 × 3 × 5
Correct answer: 2 × 2 × 3 × 7
2 × 2 × 3 × 7 × 5
2, 2, 3, 5
Q4.
The Venn diagram shows the prime factors of 60 and 84. Which calculation represents the LCM of 60 and 84?
2 × 2 × 3 × 5
Correct answer: 2 × 2 × 3 × 5 × 7
2 × 2 × 3 × 7
2 × 2 × 3 × 7 × 2 × 2 × 3 × 5
Q5.
The Venn diagram shows the prime factors of 60 and 84. What is the LCM of 60 and 84?
12