Example: 30 and 42
Factor them.
2 x 3 x 5 = 30
2 x 3 x 7 = 42
Select the common factors.
2 x 3 = 6, the GCF
The Greatest Common Divisor is 4
The Greatest Common Divisor is 28
The Greatest Common Divisor is 4
The Greatest Common Divisor is 35
The Greatest Common Divisor is 1
The Greatest Common Divisor is 2
The Greatest Common Divisor is 22
The Greatest Common Divisor is 9
The Greatest Common Divisor is 19
The Greatest Common Divisor is 10
The Greatest Common Divisor is 13
The greatest common divisor is 45.