Question

what is the greatest common factor of 65 and 91

Answer 1

13 is the greatest common factor of 65 and 91.

Answer 2

So,

First, we find the prime factored form (P.F.F.) of 65 and 91.

P.F.F. of 65: 5 * 13

P.F.F. of 91: 7 * 13

Find the common numbers
13

13 = G.C.F.

Note: This method works for finding any G.C.F. (find common primes)