Cut out the largest circle in a square piece of paper with a circumference of 100 cm. What is the area of this circle in cm**2?
在一个周长是100cm的正方形纸片内剪一个最大的圆，这个圆的面积是多少cm**2？
<gadget id="calculator">3.14 * 156.25</gadget>
<output>490.625</output>

<result>490.625</result>