How you can find the common multiples and the least common multiple?

Answer 1

Example: 30 and 42

Factor them.

2 x 3 x 5 = 30

2 x 3 x 7 = 42

Select the highest amount of each factor.

2 x 3 x 5 x 7 = 210, the LCM

Multiples of 210 will all be common multiples of 30 and 42 and can be found by multiplying 210 by successive counting numbers.

210 x 1 = 210

210 x 2 = 420

210 x 3 = 630 and so on.