Hello zpwnchenFirst, let's be clear that the word you want here is multiple, not multiply.

Secondly, there are two interpretations of , the natural numbers: it's either the positive integers, or the non-negative integers, . So unless you state which of these two definitions is being used, then it's best to avoid using here.

The clearest notation to use, then, is is a multiple of 3 and .

You could define {m, n, o, p} in a variety of ways; for example, { is a lower-case letter and followsland precedesqin alphabetical order}

Grandad