The first step to this method of finding the Least Common Multiple of 129 and 1 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 129?
Let’s take a look at the first 10 multiples for each of these numbers, 129 and 1:
First 10 Multiples of 129: 129, 258, 387, 516, 645, 774, 903, 1032, 1161, 1290
First 10 Multiples of 1: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
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 129 and 1 are 129, 258, 387. Because 129 is the smallest, it is the least common multiple.
The LCM of 129 and 1 is 129.
