GCD stands for Greatest Common Divisor. If we have two integers, the greatest common divisor is the largest integer that divides evenly into both of them. For example, 36 and 45 have a GCD of 9; and the GCD of 20 and 530 is 10. If two integers have a GCD of 1 then they have no primes in common (other than 1) and they are said to be relatively primed.

LCM stands for Least Common Multiple. If we have two integers, the least common multiple is the smallest integer that both of them divide evenly into. For example, 12 and 15 have an LCM of 60; and the LCM of 20 and 14 is 140.

Sometimes, like when we are trying to add fractions with large denominators, it is actually good to know the GCD's and LCM's of numbers. Notice that a GCD is really the same as a common denominator. That is why we offer this calculator.

Enjoy!