You might ask yourself the following question: Does the fraction terminate? To answer that question, follow these steps:

Simplify the fraction to its simplest form so that there are no shared factors among the numerator and denominator.
If there are only powers of $2$ in the denominator, it definitely terminates.
If there are only powers of $5$ in the denominator, it definitely terminates.
If there is a combination of only powers of $2$ and $5$ in the denominator, it definitely terminates.

Example

$$\frac{n}{2^45^7}$$

If $n$ is an integer -- any integer -- then the fraction above will always terminate. Test it out with some various integers.