title: Homework - Big O Notation and Calculating Time
body: <p>let's say I have an algorithm that takes 0.5ms for n = 20, and I want to figure out how long it takes if n = 40 for O(n^2).</p>
  
  <p>To my understanding, the procedure is as follows:</p>
  
  <p>t = 0.5 * (40^2/20^2)</p>
  
  <p>But why is this? I don't understand the mechanics behind this. I know that Big O is an upper bound, and for any n, its an output of some number of instructions. But calculating the time isn't making sense.</p>