How do you find 'LCM' of two rational numbers?

Answer 1

Least common multiple is defined for integers, not for rational numbers. You can find the least common multiple of the denominators, though - they are integers, and this calculation is useful for adding or subtracting fractions.

Answer 2

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