Solution: The LCM of 7 and 87 is 609
Methods
How to find the LCM of 7 and 87 using Prime Factorization
One way to find the LCM of 7 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 7?
What are the Factors of 87?
Here is the prime factorization of 7:
7
1
7^1
7 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: 7, 3, 29
3
1
×
7
1
×
2
9
1
=
609
3^1 × 7^1 × 29^1 = 609
3 1 × 7 1 × 2 9 1 = 609
Through this we see that the LCM of 7 and 87 is 609.
How to Find the LCM of 7 and 87 by Listing Common Multiples
The first step to this method of finding the Least Common Multiple of 7 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, 7 and 87:
What are the Multiples of 7?
What are the Multiples of 87?
Let’s take a look at the first 10 multiples for each of these numbers, 7 and 87:
First 10 Multiples of 7: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70
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 7 and 87 are 609, 1218, 1827. Because 609 is the smallest, it is the least common multiple.
The LCM of 7 and 87 is 609.
Find the LCM of Other Number Pairs
Want more practice? Try some of these other LCM problems:
What is the LCM of 39 and 136?
What is the LCM of 110 and 33?
What is the LCM of 19 and 35?
What is the LCM of 55 and 134?
What is the LCM of 5 and 124?