The first step to this method of finding the Greatest Common Factor of 33 and 72 is to find and list all the factors of each number. Again, you can see how this is done by looking at the “Factors of” articles that are linked to above.
Let’s take a look at the factors for each of these numbers, 33 and 72:
Factors of 33: 1, 3, 11, 33
Factors of 72: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
When you compare the two lists of factors, you can see that the common factor(s) are 1, 3. Since 3 is the largest of these common factors, the GCF of 33 and 72 would be 3.