Solution: The LCM of 1 and 21 is 21
Methods
How to Find the LCM of 1 and 21 by Listing Common Multiples
The first step to this method of finding the Least Common Multiple of 1 and 21 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 for those here:
What are the Multiples of 1?
What are the Multiples of 21?
Let’s take a look at the first 10 multiples for each of these numbers, 1 and 21:
First 10 Multiples of 1: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
First 10 Multiples of 21: 21, 42, 63, 84, 105, 126, 147, 168, 189, 210
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 1 and 21 are 21, 42, 63. Because 21 is the smallest, it is the least common multiple.
The LCM of 1 and 21 is 21.
Continue Practicing by Finding the LCM of Other Numbers
Take a look at some of our other walkthroughs, and you’ll be sure to be an expert at finding the LCM of any numbers in no time!
What is the LCM of 32 and 133?
What is the LCM of 31 and 38?
What is the LCM of 99 and 100?
What is the LCM of 93 and 28?
What is the LCM of 146 and 39?