The least common multiple of two integers a and b, is the smallest positive integer that is divisible by both a and b.

This implements a word to find this in RETRO.

It uses a formula that reduces the problem to computing the greatest common divisor (gcd), as in:

lcm(a,b) = |a*b| / gcd(a,b)

~~~:gcd (ab-n)   [ tuck mod dup ] while drop ;   :lcm (ab-n)   dup-pair gcd [ * ] dip / ; ~~~