LCM[, , ... ] gives the least common multiple of the integers .
Integer mathematical function (see Section A.3.10).
LCM also works with rational numbers; LCM[, , ... ] gives the least rational number r for which all the r/ are integers.
LCM has attributes Flat and Orderless.
See The Mathematica Book: Section 3.2.4.
See also: GCD, PolynomialLCM.