title: Binary numbers, how I can use bitmasks to certain bits?
body: <p>I have this example:</p>
  <p>If we take the binary representation of the decimal value 220 (<code>1101 1100</code>) and we wanted to extract the higher 4 bits, we could use a bitmask with the boolean AND operation:</p>
  <pre><code>      1101 1100 (220)
   AND  1111 0000 (240)
        _________
        1101 0000 (208)
  </code></pre>
  <p>I need to know how to get 240.</p>