Question: what is the greatest common factor (gcf) of 60 and 84?
Answer: The common factors of 60 and 84 are 12, 6, 4, 3, 2, 1, intersecting the two sets above. In the intersection factors of 60 ∩ factors of 84 the greatest element is 12. Therefore, the greatest common factor of 60 and 84 is 12.