Listing factors works well if the numbers don't have too many factors.

8 ---> 1, 2, 4, 8

12 ---> 1, 2, 3, 4, 6, 12

GCF (8, 12) = 4

But what if we don't want to write out all the factors.

Maybe the number has 20 factors - that would be a pain.

I'm going to show you another method using a Venn Diagram and Prime Factorization.

You'll love it!