Solution: The LCM of 123 and 87 is 3567
Methods
How to find the LCM of 123 and 87 using Prime Factorization
One way to find the LCM of 123 and 87 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 123?
What are the Factors of 87?
Here is the prime factorization of 123:
3
1
×
4
1
1
3^1 × 41^1
3 1 × 4 1 1
And this is the prime factorization of 87:
3
1
×
2
9
1
3^1 × 29^1
3 1 × 2 9 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: 3, 41, 29
3
1
×
2
9
1
×
4
1
1
=
3567
3^1 × 29^1 × 41^1 = 3567
3 1 × 2 9 1 × 4 1 1 = 3567
Through this we see that the LCM of 123 and 87 is 3567.
How to Find the LCM of 123 and 87 by Listing Common Multiples
The first step to this method of finding the Least Common Multiple of 123 and 87 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, 123 and 87:
What are the Multiples of 123?
What are the Multiples of 87?
Let’s take a look at the first 10 multiples for each of these numbers, 123 and 87:
First 10 Multiples of 123: 123, 246, 369, 492, 615, 738, 861, 984, 1107, 1230
First 10 Multiples of 87: 87, 174, 261, 348, 435, 522, 609, 696, 783, 870
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 123 and 87 are 3567, 7134, 10701. Because 3567 is the smallest, it is the least common multiple.
The LCM of 123 and 87 is 3567.
Find the LCM of Other Number Pairs
Want more practice? Try some of these other LCM problems:
What is the LCM of 142 and 102?
What is the LCM of 20 and 134?
What is the LCM of 147 and 55?
What is the LCM of 140 and 72?
What is the LCM of 107 and 8?