The front wheel of the road roller is 2 meters wide and 1 meter in diameter. If the front wheel rolls once, what is the area of the road in square meters?
压路机前轮轮宽2米，直径1米，前轮滚动一周，压路的面积是多少平方米．
<gadget id="calculator">3.14 * 1 * 2</gadget>
<output>6.28</output>

<result>6.28</result>