Least Common Multiple (LCM)

The Least Common Multiple (LCM) of two numbers is the smallest positive multiple they share in common. We have to specifically identify "positive" multiple here because of course $0$ is a multiple of every integer. 

For example, if we list out all of the positive multiples of $12$ and $18$, we will see that $36$ is the LCM:

$12$: $12$, $24$, $36$, $48$

$18$: $18$, $36$, $54$, $72$

When the two numbers are not unreasonably large, we can simply list out all of the positive multiples of each to identify the LCM. When the numbers are large, however, we have to use a different trick to find the LCM. That'll come later in your studies.