Question: what is the greatest common factor of 3 and 24?
Answer: The factors of 24 are 24, 12, 8, 6, 4, 3, 2, 1. The common factors of 3 and 24 are 3, 1, intersecting the two sets above. In the intersection factors of 3 ∩ factors of 24 the greatest element is 3. Therefore, the greatest common factor of 3 and 24 is 3.