The radius of the front wheel of the road roller is 0.5m, how many meters will it cover when it moves forward one week?
压路机前轮半径0.5m，它前进一周会压过多少米．
<gadget id="calculator">3.14 * 0.5 * 2</gadget>
<output>3.14</output>

<result>3.14</result>