Question

if you divide any multiple of 10 by 2 the answer is always 5 is that correct

Answer 1

No, it's not.

Let $x$ be ANY multple of 10. This means that $x = 10k, k \in \mathbb{Z}$.

Now, if we divide this multiple of 10 by 2, we get

$\cfrac{x}{2} = \cfrac{10k}{2} = 5k$

So, it is true that if you divide any multiple of 10 by 2 the answer is always a multiple of 5, but it doesn't mean that it has to be 5 itself.