The radius of a circular flower bed is 4 meters. If a circular pebble path with a width of 1 meter is built around it, what is the area of the pebble path?
一个圆形花坛的半径是4米，如果在其周围修一条宽1米的环形小石子路，那么小石子路的面积是多少？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">25 - 16</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<result>28.26</result>