For a beginner, you can find the multiples of a number by skip-counting to the next number. For Instance, if you want to find the multiples of 42, you could start at 42, and keep adding 42 over and over: 42, 84, 126, 168, and so on. Each of these numbers is a multiple of 42. Typically, this works best only for smaller numbers, as adding larger numbers together over and over can be difficult.
Another way to do this is to use multiplication. To find the first few multiples of 42, you could just multiply 42 by each number in sequence, first multiplying by 1, then 2, then 3, and so on, which we will outline below.