A wire is 20 cm long and encloses the largest square, what is the area of this square in square centimeters?
一根铁丝长20厘米，围一个最大的正方形，这个正方形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>