How do you work out lowest common multiple?

Answer 1

Reduce all numbers to prime factors and combine (most of each prime)

For example, LCM of 30 and 24

30 is 2 x 3 x 5

24 is 2 x 2 x 2 x 3

The most 2's we have is 3 (in 24)

The most 3's we have is 1

The most 5's we have is 1

So LCM is 2 x 2 x 2 x 3 x 5 = 120