The area of a square is 20 square centimeters, if its side length is doubled, what is its area?
一个正方形的面积是20平方厘米，如果把它的边长扩大到原来的2倍，那么它的面积是多少．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<result>80</result>