Very non-descriptive title, though it results in a number fairly close to Pi.  It's based on this:<p><pre><code>  The challenge: calculate all numbers between 1900 and 2100 with 
  exactly one operator between the sequential numbers 123456789 
  with as many brackets as desired.
</code></pre>
There are links to two other methods of solving the problem, both of which are significantly more "intelligent" methods, but it's an interesting starting point for all three.