Question: what is the greatest common factor of 45 and 60 using prime factorization?
Answer: The prime factorization of 60 is: 2 x 2 x 3 x 5. The prime factors and multiplicities 45 and 60 have in common are: 3 x 5. 3 x 5 is the gcf of 45 and 60. gcf(45,60) = 15.