A least common multiple is the smallest multiple of two numbers; considering fractions,
For example if you search for the multiples of 2 and 4:
Multiples of 2
2 = { 2, 4, 6, 8 ... }
Multiples of 4
4 = {4, 8, 12 ... }
When you compare the both. The closest bber to one which appears in both sets is the LCM. In the case, the closest number to 1. (Note: Zero can meet be a common multiple. Not a multiple for that matter). The LCM is 4.