title: Regex: How to match a string that is not only numbers
body: <p>Is it possible to write a regular expression that matches all strings that does not <em>only</em> contain numbers? If we have these strings:</p>
  
  <ul>
  <li><strong>abc</strong></li>
  <li><strong>a4c</strong></li>
  <li><strong>4bc</strong></li>
  <li><strong>ab4</strong></li>
  <li>123</li>
  </ul>
  
  <p>It should match the four first, but not the last one. I have tried fiddling around in RegexBuddy with lookaheads and stuff, but I can't seem to figure it out.</p>