Teacher Li's room is square, and its perimeter is 20 meters. What is its area?
李老师的房间是正方形的，它的周长是20米，它的面积是多少呢？
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

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

<result>25</result>