If a square is surrounded by a rope 100 meters long, what is the maximum area of the square?
用长100米的绳围一个正方形，这个正方形面积最大是多少平方米．
<gadget id="calculator">100 / 4</gadget>
<output>25</output>

<gadget id="calculator">25 * 25</gadget>
<output>625</output>

<result>625</result>