Question: what is the greatest common factor of 30 and 75 using prime factorization?
Answer: The prime factors of 30 are 5, 3 and 2. The prime numbers 5 and 3 are both factors that are common to 30 and 75. The product of these factors is 3×5 = 15. Thus, the “Greatest Common Factor” of 30 and 75 is 15.