2 Answers

The least common multiple of two or more non-zero whole numbers is actually the smallest whole number that is divisible by each of the numbers.

Simply list the multiples of each number (multiply by 2, 3, 4, etc.) then look for the smallest number that appears in each list.

Example: Find the least common multiple for 5, 6, and 15. First we list the multiples of each number.

Multiples of 5 are 10, 15, 20, 25, 30, 35, 40,...

Multiples of 6 are 12, 18, 24, 30, 36, 42, 48,...

Multiples of 15 are 30, 45, 60, 75, 90,....

Now, when you look at the list of multiples, you can see that 30 is the smallest number that appears in each list.

Therefore, the least common multiple of 5, 6 and 15 is 30.

Do you Understand now?

The only additional comment I would make to what Jack Large has told you is that
LEAST (sometimes called LOWEST) COMMON MULTIPLE is a PRODUCT (the answer in multiplication).
It might be a little confusing when you see the word "divisible" in the definition he gave.
In other words, the smallest number that all of them are factors of (factor being a number that is multiplied by another factor....number....to reach a product).