Greatest common divisor

The greatest common divisor (GCD) or greatest common factor of two natural numbers is the largest natural number which divides them both. For example, the greatest common divisor of 62 and 64 is 2 since no bigger number divides both 62 and 64, even though larger numbers divide 62 and 64. Sometimes the notation (62,64)=2 is used. The Euclidean algorithm calculates greatest common divisors.