title: Excel Number Formatting
body: <p>I'm currently working on a sheet that contains part numbers in it.  I'd like them to be formatted like this:</p>
  
  <pre><code>@@@@-#####-XX
  </code></pre>
  
  <p>Where @s can be letters or numbers, #s are numbers, and Xs are letters.</p>
  
  <p>I run into two problems while doing this.  The first is that I can't figure out how to handle text and numbers at the same time in the Custom Format dialog box.  The second is that occasionally a part number will have 3 letters after the second hyphen rather than 2, and I can't figure out how I should structure the condition to differentiate between the two formats.</p>
  
  <p>How can I handle numbers and text at the same time when creating a custom format, and how can I add the condition described above (based on character numbers or something)?</p>
  
  <p>Thanks.</p>