title: Remove decimal places to certain digits without rounding
body: <p>I've found dozen of answers, but non of them is what I'm looking for, I don't want to round up or down, I know that I can round numbers as follow:</p>
  
  <pre><code>&gt;&gt;&gt; print('%.3f' % 15.555555)
  15.556
  
  &gt;&gt;&gt; round(15.555555, 3)
  15.666
  </code></pre>
  
  <p>But I need to get 15.555. Should I use regex?</p>