How can you use the prime factorization of two numbers to find their least common factor?

Answer 1

Example: 30 and 42

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

Answer 2

You don't need to. The least common factor of any set of positive integers is 1.