title: Convert the following expression to use only NAND gates
body: <p>I have the following expression ( <code>'</code>denotes <code>NOT</code>)...</p>
  
  <pre><code>e'(a+b)
  </code></pre>
  
  <p>First I expand...</p>
  
  <pre><code>e'a + e'b
  </code></pre>
  
  <p>DeMorgan's Law...</p>
  
  <pre><code>(e'a +e'b)'
  ((e'a)'(e'b)')'
  </code></pre>
  
  <p>Now I am stuck. Each <code>NAND</code> gate that I use can only accept a maximum of 2 inputs. I can use as many <code>NAND</code> gates as I want, but I should try to come up with an expression that uses the least amount of gates.</p>
  
  <p>Am I on the right track? How do I continue further?</p>