title: Javascript (+) sign concatenates instead of giving sum of variables
body: <p>Why when I use this: (assuming <code>i = 1</code>)</p>
  
  <pre><code>divID = "question-" + i+1;
  </code></pre>
  
  <p>I get <strong>question-11</strong> and not <strong>question-2</strong>?</p>