How do you find the LCD and LCM?

Answer 1

Example: 30 and 42

Factor them.

2 x 3 x 5 = 30

2 x 3 x 7 = 42

Combine the factors, eliminating duplicates.

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

The LCD is the same process, except it's a denominator.