title: SQL Server POWER function
body: <p>Using SQL Server 2008 R2 when I enter the following query:</p>
  
  <pre><code>SELECT CAST(POWER(2.0, 63.0) AS BIGINT);
  </code></pre>
  
  <p>Which yields the result:</p>
  
  <pre><code>9223372036854775800
  </code></pre>
  
  <p>However, using the Windows desktop calculator and raising 2 to the 63 yields:</p>
  
  <pre><code>9223372036854775807
  </code></pre>
  
  <p>Can someone please explain the difference -- or is there some internal conversion that SQL Server is doing? ... or am I missing something else?</p>