Question: what is the greatest common factor of 16 and 64?
Answer: The prime factorization of 64 is: 2 x 2 x 2 x 2 x 2 x 2. The prime factors and multiplicities 16 and 64 have in common are: 2 x 2 x 2 x 2. 2 x 2 x 2 x 2 is the gcf of 16 and 64. gcf(16,64) = 16.