The diameter of the circular musical fountain in the park is 20 meters, and a 2-meter-wide cobblestone road is paved around the fountain. How many square meters does the cobblestone road cover?
公园圆形音乐喷泉的直径是20米，在喷泉周围铺上2米宽的鹅卵石路，鹅卵石路占地多少平方米？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 + 2</gadget>
<output>12</output>

<gadget id="calculator">12 ** 2</gadget>
<output>144</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">144 - 100</gadget>
<output>44</output>

<gadget id="calculator">3.14 * 44</gadget>
<output>138.16</output>

<result>138.16</result>