title: Math.Sqrt() when using BigInteger?
body: <p>I need to make a <code>Math.Sqrt</code> calculation but it must support really big numbers so I'm trying to use <code>BigInteger</code> but <code>Math.Sqrt</code> doesn't support them. </p>
  
  <p>Are there any other options? How can I do this calculation  and result is double ?</p>
  
  <p>Sample :</p>
  
  <pre><code>sqrt 5 = 2,2360679774997896964091736687313 
  sqrt 4789798765456456456 = xxxxx,xxxxxxxxxxx norm.
  </code></pre>