If the perimeter of a square is 20 centimeters, what is its area in square centimetres?
正方形的周长20厘米，它的面积是多少平方厘米．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

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

<result>25</result>