title: Regular expression for first 4 characters
body: <p>I need a regular expression for 4 characters. The first 3 characters must be a number and the last 1 must be a letter or a digit.</p>
  
  <p>I formed this one, but it not working</p>
  
  <pre><code>^([0-9]{3}+(([a-zA-Z]*)|([0-9]*)))?$
  </code></pre>
  
  <p>Some valid matches: <code>889A</code>, <code>777B</code>, <code>8883</code></p>