title: Multiply two fields together in django
body: <p>I have the following query:</p>
  
  <pre><code>sales_for_date_for_provider.exclude(sales_or_return='R').values_list('royalty_price', 'conversion_to_usd'))
  </code></pre>
  
  <p>Is it possible to multiple the <code>royalty_price</code> * <code>conversion_to_usd</code> in the query? Or do I need to do a list comprehension or dive into raw SQL?</p>