The roller of the road roller is 3 meters long and the radius of the bottom surface is 0.5 meters. How many square meters of road surface can be pressed by the roller in one revolution?
压路机的滚筒长3米，底面半径为0.5米，滚筒转动一周可以压路面多少平方米？
<gadget id="calculator">2 * 3.14 * 0.5</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 * 3</gadget>
<output>9.42</output>

<result>9.42</result>