Question: why are gcf and lcm useful?
Answer: A common use of the GCF is to simplify a fraction by dividing both the numerator and denominator by the GCF of both. Another way to find the LCM for two numbers is to divide the product of the two numbers by the GCF for the numbers. For example, the GCF of 36 and 60 is 12. The product of 36 x 60 = 2,160.