A circular flower belt with a width of 1 meter is built around a circular fountain with a radius of 20 meters. What is the area of the circular flower belt in square meters?
在一个半径为20米的圆形喷水池的周围修一条宽1米的环形花带，这个环形花带的面积是多少平方米？
<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">21 ** 2</gadget>
<output>441</output>

<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">441 - 400</gadget>
<output>41</output>

<gadget id="calculator">3.14 * 41</gadget>
<output>128.74</output>

<result>128.74</result>