Draw the largest circle in a square with side length 5 cm, the area of the circle is equal to the area of the square.
在边长是5cm的正方形内画一个最大的圆，该圆的面积是这个正方形面积的多少．
<gadget id="calculator">6.25 / 25</gadget>
<output>0.25</output>

<gadget id="calculator">3.14 * 0.25</gadget>
<output>0.785</output>

<result>0.785</result>