There are 20 stickers on a page. If you have 12 pages of stickers but lose one of the pages, then how many stickers would you have?
After losing one of the pages you have 12 - 1 = 
<gadget id="calculator">12-1</gadget>
<output>11</output>
11 pages of stickers.
If each page has 20 stickers on it, you have 11 x 20 = 
<gadget id="calculator">11*20</gadget>
<output>220</output>
220 stickers.

<result>220</result>