Actually, there are infinitely many rational numbers between them, but let's take the one "in the middle".
so the number between 1 and 2 is 1.5
so the number between them would be

but since this is not a proper way of writing it, we should multiply both sides by something to get rid of the Point, let's say we multiply it by 2.
and this is an example of a rational number between-1/6 and -2/6