Phil likes to collect baseball cards.  He buys a pack of twenty each week for a year, but then loses half of them one day in a fire.  How many baseball cards does Phil have left?
Since there are 20 cards in a pack and 52 weeks in a year, Phil starts by collecting 20*52= 
<gadget id="calculator">20*52</gadget>
<output>1_040</output>
1040 baseball cards.
He then loses half of them for 1040/2= 
<gadget id="calculator">1040/2</gadget>
<output>520</output>
520 cards remaining.

<result>520</result>