title: Modular multiplication of large numbers
body: <p>I need to find an efficient algorithm for doing modular multiplication of three numbers.</p>
  
  <p>In other words is there a way to find this in C?</p>
  
  <pre><code>(100100101010001001 * 1010000100100010 * 10010001001010100101001) % 1000000007
  </code></pre>