The Problem Statement:
You are creating a program to help you understand some important math concepts: factorials and exponents.
Since you are focused on understanding the concepts, you will not use the math library (math.h).
One of those sections will be the function to calculate a factorial.
Your function will take in a single non-negative integer (n) and you'll calculate n! or n factorial.
To calculate n! you would calculate the following product: 1x2x3x...xn.
