The radius of a circular lawn is 40 meters, and a 10-meter-wide cement road is built around the lawn. What is the area of this road in square meters?
一个圆形草坪的半径是40米，草坪的周围修有一条10米宽的水泥马路．这条马路的面积是多少平方米？
<gadget id="calculator">40 + 10</gadget>
<output>50</output>

<gadget id="calculator">50 ** 2</gadget>
<output>2_500</output>

<gadget id="calculator">3.14 * 2_500</gadget>
<output>7_850</output>

<gadget id="calculator">40 ** 2</gadget>
<output>1_600</output>

<gadget id="calculator">3.14 * 1_600</gadget>
<output>5_024</output>

<gadget id="calculator">7_850 - 5_024</gadget>
<output>2_826</output>

<result>2_826</result>