Calculating time of execution with time() function

Question

I was given the following HomeWork assignment,

Write a program to test on your computer how long it takes to do nlogn, n2, n5, 2n, and n! additions

Answer 1

Execute each calculation thousands of times, in a loop, so that you can overcome the low resolution of time and obtain meaningful results. Remember to divide by the number of iterations when reporting results.

This is not particularly accurate but that probably does not matter for this assignment.