What is the GCF of 45 18 39?

The factors of 18 are:

1, 2, 3, 6, 9, 18

The factors of 39 are:

1, 3, 13, 39

The factors of 45 are:

1, 3, 5, 9, 15, 45

The common factors are:

1, 3

The Greatest Common Factor (GCF) is:

3