Question: what is the greatest common factor of 44 and 11?
Answer: The factors of 44 are 44, 22, 11, 4, 2, 1. The factors of 11 are 11, 1. The common factors of 44 and 11 are 11, 1, intersecting the two sets above. In the intersection factors of 44 ∩ factors of 11 the greatest element is 11. Therefore, the greatest common factor of 44 and 11 is 11.