title: Add +1 to a string obtained from another site
body: <p>I have a string I get from a website.</p>
  
  <p>A portion of the string is "X2" I want to add +1 to 2.</p>
  
  <p>The entire string I get is:</p>
  
  <pre><code>20120815_00_X2
  </code></pre>
  
  <p>What I want is to add the "X2" +1 until "20120815_00_X13"</p>