The least common multiple (LCM) of two
integers
a and
b is the smallest positive integer that is a multiple of both
a and
b. If there is no such positive integer, i.e. if either
a or
b is zero, then
then LCM(
a,
b) is defined to be zero.
In case not both a and b are zero, the least common multiple can be computed by using the greatest common divisor (or GCD) of a and b,
| a b |
LCM(a, b) = |
|
| GCD(a, b) |
Thus, Euclid's algorithm for GCD gives us a fast algorithm for LCM. As an example, the LCM of 12 and 15 is 12 * 15 / 3 = 60.