A road roller has a cylindrical front wheel with a width of 2 meters and a radius of 0.5 meters. How many square meters is the area of the road when the front wheel rotates once?
一台压路机的前轮是圆柱形，轮宽2米，半径0.5米．前轮转动一周，压路的面积是多少平方米？
<gadget id="calculator">2 * 3.14 * 0.5 * 2</gadget>
<output>6.28</output>

<result>6.28</result>