title: Factorial of factorial of a number
body: <p>How can the factorial of a factorial of a number be efficiently computed.<br>
  Example:For 3 => (3!)! = (6)! = 720<br>
  The brute force way would be to simply call factorial twice using a simple for loop but can it be done better.</p>
  
  <pre><code>for(i=1;i&lt;=n;i++) 
     fact=fact*i; 
  </code></pre>
  
  <p>Edit: Need the result as ((n!)!)MOD 10^m, where m is an integer and 0&lt;=m&lt;=19</p>