Solution: The LCM of 55 and 77 is 385
Methods
How to find the LCM of 55 and 77 using Prime Factorization
One way to find the LCM of 55 and 77 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 55?
What are the Factors of 77?
Here is the prime factorization of 55:
5
1
×
1
1
1
5^1 × 11^1
5 1 × 1 1 1
And this is the prime factorization of 77:
7
1
×
1
1
1
7^1 × 11^1
7 1 × 1 1 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: 5, 11, 7
5
1
×
7
1
×
1
1
1
=
385
5^1 × 7^1 × 11^1 = 385
5 1 × 7 1 × 1 1 1 = 385
Through this we see that the LCM of 55 and 77 is 385.
How to Find the LCM of 55 and 77 by Listing Common Multiples
The first step to this method of finding the Least Common Multiple of 55 and 77 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, 55 and 77:
What are the Multiples of 55?
What are the Multiples of 77?
Let’s take a look at the first 10 multiples for each of these numbers, 55 and 77:
First 10 Multiples of 55: 55, 110, 165, 220, 275, 330, 385, 440, 495, 550
First 10 Multiples of 77: 77, 154, 231, 308, 385, 462, 539, 616, 693, 770
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 55 and 77 are 385, 770, 1155. Because 385 is the smallest, it is the least common multiple.
The LCM of 55 and 77 is 385.
Find the LCM of Other Number Pairs
Want more practice? Try some of these other LCM problems:
What is the LCM of 126 and 71?
What is the LCM of 28 and 124?
What is the LCM of 61 and 106?
What is the LCM of 19 and 78?
What is the LCM of 17 and 65?