Question: what is a greatest common factor of 14 and 11?
Answer: The factors of 14 are 14, 7, 2, 1. The factors of 11 are 11, 1. The common factors of 14 and 11 are 1, intersecting the two sets above. In the intersection factors of 14 ∩ factors of 11 the greatest element is 1. Therefore, the greatest common factor of 14 and 11 is 1.