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 3 using this method, you could start at 3, and keep adding 3 over and over: 3, 6, 9, 12, and so on. Each of these numbers is a multiple of 3. 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 3. To find the first few multiples of 3, you could just multiply the 3 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.