Year 7 Interactive Maths - Second Edition

Lowest Common Multiple

E.g. Multiples of 8 are 8, 16, 24, 32, …
       Multiples of 3 are 3, 6, 9, 12, 15, 18, 21, 24, …

In general:

To find the lowest common multiple (LCM) of two or more numbers, list the multiples of the larger number and stop when you find a multiple of the other number.  This is the LCM.

Example 3

Find the lowest common multiple of 6 and 9.

Solution:

List the multiples of 9 and stop when you find a multiple of 6.

Multiples of 9 are 9, 18, …
Multiples of 6 are 6, 12, 18, …

Example 4

Find the lowest common multiple of 5, 6 and 8.

Solution:

List the multiples of 8 and stop when you find a multiple of both 5 and 6.

Multiples of 8 are 8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, …

Stop at 120 as it is a multiple of both 5 and 6.

So, the LCM of 5, 6 and 8 is 120.

Key Terms

lowest common multiple, LCM