title: Why prefer start + (end - start) / 2 over (start + end) / 2 when calculating the middle of an array?
body: <p>I've seen programmers use the formula</p>
  
  <pre><code>mid = start + (end - start) / 2
  </code></pre>
  
  <p>instead of using the simpler formula</p>
  
  <pre><code>mid = (start + end) / 2
  </code></pre>
  
  <p>for finding the middle element in the array or list.</p>
  
  <p>Why do they use the former one?</p>