What is the area of a circular flower pond with a radius of 4 meters?
一个圆形花池，半径4米，它的面积是多少？
<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>