Question: what is the least common factor for 10 and 60?
Answer: The prime factorization of 10 is: 2 x 5.
The prime factorization of 60 is: 2 x 2 x 3 x 5.
Eliminate the duplicate factors of the two lists, then multiply them once with the remaining factors of the lists to get lcm(10,10) = 60.