To get started with multiples, the easiest way is just to add a number to itself over and over again. For instance, if you want to find the multiples of 18 using this method, you could start at 18, and keep adding 18 over and over: 18, 36, 54, 72, and so on. Each of these numbers is a multiple of 18. Usually, this method works with numbers that are easily added to itself. As you get into larger numbers, it can become difficult to continue adding.
Another way to do this, as discussed above, is to use choose any number and multiply it by 18. To find the first few multiples of 18, you could just multiply the 18 by 1, then 2, then 3, and so on, until you have as many multiples as you would like.
There are an endless number of multiples! You can keep using either of these methods to find as many multiples as you would like.