Exponential Notation is an easier way to write a number as a product of many factors. The exponent tells us how many times the base is used as a factor.
Now onto the actual problem.
First, you can factor out 625 using the "tree" method or the "ladder" method.
625
/ \
5 125
/ \
5 25
/ \
5 5
This means you can say that 625=5 to the power of 4.
If your problem requires you only use whole intergers with exponents, then that would be the only way.
If not you can do, 625 = 25*5²
Hope this helps you =)
