title: How does this coin change algorithm work?
body: <p>Here is a list of coin denominations ordered from high to low.</p>
  
  <pre><code>coinage = [500, 200, 100, 50, 20, 10, 5, 1]
  </code></pre>
  
  <p>and the amount of money is <strong>445</strong>. The output of this function is </p>
  
  <pre><code>[(2, 200), (2, 20), (1, 5)]
  </code></pre>
  
  <p>I'm really confused about the algorithm. How does it work?</p>