What is the area of a square with a side length of 20 cm?
一个正方形，边长是20厘米，面积是多少平方分米．
<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<gadget id="calculator">400 / 100</gadget>
<output>4</output>

<result>4</result>