LCM( 15, 20 ) = 60
Write down multiples of each number until you find the first common multiple:
The multipliers of 15 are: 15, 30, 45, 60, 75, . . .
The multipliers of 20 are: 20, 40, 60, 80, . . .
We can see that:
LCM( 15, 20 ) = 60
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.