title: OrderBy custom comparer specific letters before numbers
body: <p>Say I have the following List:</p>
  
  <pre><code>var lettersAndNumbers = new List&lt;string&gt; { "5", "kl", "1", "st", "3" };
  </code></pre>
  
  <p>How do I use <code>OrderBy</code> to sort the list, where I can specify that <code>kl</code> should be the first item, <code>st</code> the next, and the remaining sequence should be ordered by numbers lowest to highest?</p>
  
  <p>I know that I need to use a custom <code>comparer</code>. I have tried and created a <code>comparer</code> class implementing <code>ICompareable</code>, but I can't seem to make it work. Any help is much appreciated.</p>