A square of 80 cm long is surrounded by an iron wire. What is the area of the square in square centimeters?
将一根80厘米的铁丝围成一个正方形，这个正方形的面积是多少平方厘米．
<gadget id="calculator">80 / 4</gadget>
<output>20</output>

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

<result>400</result>