title: C# string manipulation problem
body: <p>Here's a simple problem.  I have an application that takes a phone number like "13335557777", and needs to reverse it and insert a dot between each number, like this:</p>
  
  <p>"7.7.7.7.5.5.5.3.3.3.1."</p>
  
  <p>I know I can do this with a StringBuilder and a for-loop to reverse the string and insert the dots, but is there a clever way to do this in LINQ (or some other way)?</p>
  
  <p>Note: for this, I'm not really concerned with performance or memory allocation or whatever, just curious to see how this would be done in LINQ.</p>