*least common multiple*(LCM) of two or more numbers is the smallest number (not zero) that's a multiple of both or all the numbers. Finding the LCM is a useful technique for solving many problems on the ASVAB AFQT math subtestsâ€”especially those involving fractions.

One way to find the LCM is to list the multiples of each number, one at a time, until you find the smallest multiple that's common to all the numbers.

Try the following example: find the LCM of 45 and 50.

**Multiples of 45:**45, 90, 135, 180, 225, 270, 315, 360, 405, 450**Multiples of 50:**50, 100, 150, 200, 250, 300, 350, 400, 450

That's rather cumbersome, isn't it? Wouldn't it be great if you had an easier way? Fortunately, you do: An easier way to find the LCM is first to list the prime factors of each number:

- The prime factors for 45 are
- The prime factors for 50 are

Here's one more example: what is the least common multiple of 5, 27, and 30?

List the prime factors of each number:

**Prime factors of 5:**5

**Prime factors of 27:**

**Prime factors of 30:**

The number 3 occurs a maximum of three times, 5 occurs a maximum of one time, and 2 occurs a maximum of one time:

Check your answer by seeing whether 5, 27, and 30 can all divide evenly into 270.