Mr. Zhang bought 22 story books, each of which was 16 yuan, and paid 400 yuan. How much should we get back?
张老师买了22本故事书，每本16元，付了400元，应找回多少元．
<gadget id="calculator">16 * 22</gadget>
<output>352</output>

<gadget id="calculator">400 - 352</gadget>
<output>48</output>

<result>48</result>