title: Help with drivers license number validation regex
body: <p>I'm trying to validate a drivers license for a form that i am making.
  I was trying to use a single regex.</p>
  
  <ol>
  <li>Max length 9 characters</li>
  <li>Alphanumeric characters only</li>
  <li>Must have at least 4 numeric characters</li>
  <li>Must have no more than 2 alphabetic characters</li>
  <li>The third and fourth character must be numeric </li>
  </ol>
  
  <p>I'm new at regex I'm googling trying to work it out. Help with this would be appreciated.</p>