Question: what is a greatest common factor of 4 and 76?
Answer: The factors of 76 are 76, 38, 19, 4, 2, 1. The common factors of 4 and 76 are 4, 2, 1, intersecting the two sets above. In the intersection factors of 4 ∩ factors of 76 the greatest element is 4. Therefore, the greatest common factor of 4 and 76 is 4.