Solution: The LCM of 28 and 121 is 3388
Methods
How to find the LCM of 28 and 121 using Prime Factorization
One way to find the LCM of 28 and 121 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 28?
What are the Factors of 121?
Here is the prime factorization of 28:
2
2
×
7
1
2^2 × 7^1
2 2 × 7 1
And this is the prime factorization of 121:
1
1
2
11^2
1 1 2
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, 7, 11
2
2
×
7
1
×
1
1
2
=
3388
2^2 × 7^1 × 11^2 = 3388
2 2 × 7 1 × 1 1 2 = 3388
Through this we see that the LCM of 28 and 121 is 3388.
How to Find the LCM of 28 and 121 by Listing Common Multiples
The first step to this method of finding the Least Common Multiple of 28 and 121 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, 28 and 121:
What are the Multiples of 28?
What are the Multiples of 121?
Let’s take a look at the first 10 multiples for each of these numbers, 28 and 121:
First 10 Multiples of 28: 28, 56, 84, 112, 140, 168, 196, 224, 252, 280
First 10 Multiples of 121: 121, 242, 363, 484, 605, 726, 847, 968, 1089, 1210
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 28 and 121 are 3388, 6776, 10164. Because 3388 is the smallest, it is the least common multiple.
The LCM of 28 and 121 is 3388.
Find the LCM of Other Number Pairs
Want more practice? Try some of these other LCM problems:
What is the LCM of 130 and 146?
What is the LCM of 124 and 91?
What is the LCM of 44 and 131?
What is the LCM of 86 and 46?
What is the LCM of 39 and 4?