Solution: The LCM of 87 and 85 is 7395
Methods
How to find the LCM of 87 and 85 using Prime Factorization
One way to find the LCM of 87 and 85 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 87?
What are the Factors of 85?
Here is the prime factorization of 87:
3
1
×
2
9
1
3^1 × 29^1
3 1 × 2 9 1
And this is the prime factorization of 85:
5
1
×
1
7
1
5^1 × 17^1
5 1 × 1 7 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, 29, 5, 17
3
1
×
5
1
×
1
7
1
×
2
9
1
=
7395
3^1 × 5^1 × 17^1 × 29^1 = 7395
3 1 × 5 1 × 1 7 1 × 2 9 1 = 7395
Through this we see that the LCM of 87 and 85 is 7395.
How to Find the LCM of 87 and 85 by Listing Common Multiples
The first step to this method of finding the Least Common Multiple of 87 and 85 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, 87 and 85:
What are the Multiples of 87?
What are the Multiples of 85?
Let’s take a look at the first 10 multiples for each of these numbers, 87 and 85:
First 10 Multiples of 87: 87, 174, 261, 348, 435, 522, 609, 696, 783, 870
First 10 Multiples of 85: 85, 170, 255, 340, 425, 510, 595, 680, 765, 850
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 87 and 85 are 7395, 14790, 22185. Because 7395 is the smallest, it is the least common multiple.
The LCM of 87 and 85 is 7395.
Find the LCM of Other Number Pairs
Want more practice? Try some of these other LCM problems:
What is the LCM of 138 and 124?
What is the LCM of 142 and 128?
What is the LCM of 115 and 5?
What is the LCM of 110 and 27?
What is the LCM of 26 and 61?