Least Common Multiple

There are three different methods that we can use to find the Least Common Multiple of a set of numbers.

Method 1: Use a Number Line

Method 2: Use a List of Multiples

Method 3: Use Prime Factorization

Here are some examples of how each method can be used to find the Least Common Multiple of a set of numbers.

Method 1: The Number Line Method

To use a number line in finding the least common multiple of a group of numbers, you must basically count by that number as you make your way down the number line. This method may be helpful for those students who have trouble with their multiplication facts.

The downside to this method is that it can take a long time to draw the number line and find the least common multiple. It also takes up a great deal of space in your notebook. If you are trying to find the LCM of more than two numbers or if the set of numbers that you are given contains numbers larger than ten, then I would recommend a different method to find the LCM.

As you can see from the sample above, the student still had to find the multiples of each number using the list method. This also gives you an idea of how much space this method could really take.

images from the Oakland Terrace Elementary School website

Method 2: Listing Multiples

To find the LCM of  2, 3, and 6

Create a list of multiples for each number in the group by multiplying by whole numbers greater than zero.

2: 2, 4, 6
3: 3, 6
6: 6,

LCM of 2, 3, and 6 = 6

Method 3: Prime Factorization

Here are some links that will give you more examples of finding the Least Common Multiple
Least Common Multiple Power Point: Click Here to View
More Examples from Mc Graw Hill: Click Here to View