Question: what is the greatest common factor of 44?
Answer: The prime factorization of 44 is: 2 x 2 x 11.
The prime factorization of 40 is: 2 x 2 x 2 x 5.
The prime factors and multiplicities 44 and 40 have in common are: 2 x 2.
2 x 2 is the gcf of 44 and 40.
gcf(44,40) = 4.