Write down multiples of each number until you find the first common multiple:

The multipliers of 12 are: 12, 24, 36, 48, 60, 72, 84, 96, . . .

The multipliers of 14 are: 14, 28, 42, 56, 70, 84, 98, . . .

We can see that:

LCM( 12, 14 ) = 84

This solution can be visualized using a Venn diagram.

The LCM is equal to the product of all the numbers on the diagram.