What is the greatest common factor of 42, 126, and 210?

The GCF = 42

The prime factors of 42 = 2,3,7

The prime factors of 126 = 2, 3, 3, 7

The prime factors of 210 = 2,3 ,5, 7

The common values are ##2*3*7= 42##

The GCF = 42