Solution: The LCM of 18 and 69 is 414
Methods
How to find the LCM of 18 and 69 using Prime Factorization
One way to find the LCM of 18 and 69 is to start by comparing the prime factorization of each number. To find the prime factorization, you can follow the instructions for each number here:
What are the Factors of 18?
What are the Factors of 69?
Here is the prime factorization of 18:
2
1
×
3
2
2^1 × 3^2
2 1 × 3 2
And this is the prime factorization of 69:
3
1
×
2
3
1
3^1 × 23^1
3 1 × 2 3 1
When you compare the prime factorization of these two numbers, you want to look for the highest power that each prime factor is raised to. In this case, there are these prime factors to consider: 2, 3, 23
2
1
×
3
2
×
2
3
1
=
414
2^1 × 3^2 × 23^1 = 414
2 1 × 3 2 × 2 3 1 = 414
Through this we see that the LCM of 18 and 69 is 414.
How to Find the LCM of 18 and 69 by Listing Common Multiples
The first step to this method of finding the Least Common Multiple of 18 and 69 is to begin to list a few multiples for each number. If you need a refresher on how to find the multiples of these numbers, you can see the walkthroughs in the links below for each number.
Let’s take a look at the multiples for each of these numbers, 18 and 69:
What are the Multiples of 18?
What are the Multiples of 69?
Let’s take a look at the first 10 multiples for each of these numbers, 18 and 69:
First 10 Multiples of 18: 18, 36, 54, 72, 90, 108, 126, 144, 162, 180
First 10 Multiples of 69: 69, 138, 207, 276, 345, 414, 483, 552, 621, 690
You can continue to list out the multiples of these numbers as long as needed to find a match. Once you do find a match, or several matches, the smallest of these matches would be the Least Common Multiple. For instance, the first matching multiple(s) of 18 and 69 are 414, 828, 1242. Because 414 is the smallest, it is the least common multiple.
The LCM of 18 and 69 is 414.
Find the LCM of Other Number Pairs
Want more practice? Try some of these other LCM problems:
What is the LCM of 46 and 140?
What is the LCM of 84 and 39?
What is the LCM of 130 and 147?
What is the LCM of 100 and 135?
What is the LCM of 72 and 88?