The perimeter of a square is 20 decimeters, what is its area in square decimeters
一个正方形的周长是20分米，它的面积是多少平方分米
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<result>25</result>