Question: what is the greatest common factor between 30 and 77?
Answer: The prime factorization of 30 is: 2 x 3 x 5.
The prime factorization of 77 is: 7 x 11.
The prime factors and multiplicities 30 and 77 have in common are: 1.
1 is the gcf of 30 and 77.
gcf(30,77) = 1.