A circular flower bed has a radius of 20 meters. Now it is planned to build a 3-meter-wide walkway outside the park. How many square meters does the walkway cover?
一个圆形花坛，半径长20米，现在计划在公园的外围修一条3米宽的步道，步道的占地面积是多少平方米？
<gadget id="calculator">20 + 3</gadget>
<output>23</output>

<gadget id="calculator">23 ** 2</gadget>
<output>529</output>

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

<gadget id="calculator">529 - 400</gadget>
<output>129</output>

<gadget id="calculator">3.14 * 129</gadget>
<output>405.06</output>

<result>405.06</result>