The front wheel of a road roller is cylindrical, the width of the wheel is 2.5 meters, and the diameter is 0.8 meters. How many square meters is the area of the road when the front wheel rotates once?
一辆压路机的前轮是圆柱形，轮宽2.5米，直径是0.8米．前轮转动一周，压路的面积是多少平方米？
<gadget id="calculator">3.14 * 0.8 * 2.5</gadget>
<output>6.28</output>

<result>6.28</result>