title: sed calculations
body: <p>I want to parse a css file and multiply each pixel value by (2/3).  I was wondering if this was possible with sed?  I know this is incorrect syntax but i think it'll bring home the explanation of what i want to achieve:</p>
  
  <pre><code>sed -e "s|\([0-9]*\)px|int((\1 * 2)/3)|g" file.css
  </code></pre>
  
  <p>So basically I want to take \1, multiply it by (2/3) and cast to and int.  Or maybe it's more possible with awk?  Suppose I could write a python script, but would like to know if it can be done by quicker means.</p>
  
  <p>Thanks</p>