Question: what is the greatest common factor of 72 and 84 using prime factorization?
Answer: The prime factorization of 84 is: 2 x 2 x 3 x 7. The prime factors and multiplicities 72 and 84 have in common are: 2 x 2 x 3. 2 x 2 x 3 is the gcf of 72 and 84. gcf(72,84) = 12.