circular fountain with a diameter of 20m. Now build a path with a width of 1m around the fountain. How many square meters does the path occupy?
一个圆形喷水池，直径是20m．现在绕着喷水池周围修一条宽1m的小路．小路的占地面积是多少平方米？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<gadget id="calculator">11 ** 2</gadget>
<output>121</output>

<gadget id="calculator">3.14 * 121</gadget>
<output>379.94</output>

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

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">379.94 - 314</gadget>
<output>65.94</output>

<result>65.94</result>