title: python float precision issue
body: <p>I encountered a strange float number problem of python(2.7.3).</p>
  
  <pre><code>In [4]: 17 * 0.1
  Out[4]: 1.7000000000000002
  </code></pre>
  
  <p>but</p>
  
  <pre><code>In [5]: print(17*0.1)
  1.7
  </code></pre>
  
  <p>Two questions:</p>
  
  <ol>
  <li>why <code>17*0.1</code> is <code>1.7000000000000002</code> ?</li>
  <li>why <code>print</code> is fine?</li>
  </ol>