What numbers are divisible by 3 and 8?

Lots and lots of them are. But a good way to determine which ones are is to multiply 3 x 8, which = 24. Then you can multiply 24 x 3 or 24 x 8, and then each of those answers will be divisible by 3 and by 8.

You can then multiply those numbers by 3 and/or 8, which will also be divisible by 3 and 8, and on and on....
24 and any multiples, plus others...