To express the number 8125 as a fraction, we can represent it as a fraction over 1. This is because any whole number can be written as a fraction by placing it over 1. Therefore, 8125 can be written as:
8125/1
In this form, 8125 is both the numerator and the denominator indicates that it is a whole number. This fraction cannot be simplified further since 1 is the only divisor of itself. Thus, the simplest form of 8125 as a fraction is 8125/1.