What are the multiple of 3 after 20?

Answer 1

There are infinitely many of them so they cannot be listed. You can start with 21 and keep adding 3 until you have had enough of it.

Answer 2

Using the definition of "multiple", you can multiply 3 by different integers.Also, once you have one multiple of 3, you can add 3 to get additional multiples.

Answer 3

21, 24, 27 and so on.