What is the greatest common factor of 65 and 91

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)

13 is the greatest common factor of 65 and 91.