title: parse a string to find a number greater than a certain length
body: <p>I have a string which is essentially a filename.
  Our annoying end users decided that they want to somewhere within the filename put our product code if they feel like it. 
  Now the only way that I can think of getting this is to look for a number within a string where the number length is greater than 4. An example is below but i'm unsure how to check whether a string contains a number with a length greater than 4 or not. </p>
  
  <pre><code>73767 Carex Wipes Clipstrip Pack - Strawberry Laces.xlsm
  </code></pre>