There is a square lotus pond in the garden. Its circumference is 80 meters, please do the math, how many square meters is its area?
花园里有一个正方形的荷花池．它的周长是80米，请你算一算，它的面积是多少平方米？
<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<result>400</result>