title: printf, sprintf print at least two decimal places
body: <p>I'm trying to figure out how to use sprintf to print at least two decimal places and no leading zeros.  For instance</p>
  
  <p>input:</p>
  
  <pre><code>23
  23.0
  23.5
  23.55
  23.555
  23.0000
  </code></pre>
  
  <p>output:</p>
  
  <pre><code>23.00
  23.00
  23.50
  23.55
  23.555
  23.00
  </code></pre>
  
  <p>any formatting help would be appreciated</p>