The school wants to build a gravel road with a width of 2 meters around a circular fountain with a diameter of 8 meters. Calculate the area of this road in square meters.
学校要在一个直径为8米的圆形喷水池的周围修一条宽2米的石子路，算一算这条路的面积是多少平方米．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 2</gadget>
<output>6</output>

<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

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

<gadget id="calculator">36 - 16</gadget>
<output>20</output>

<gadget id="calculator">3.14 * 20</gadget>
<output>62.8</output>

<result>62.8</result>