The diameter of the roller is 1.8m. If it rolls 20 times per minute, how many meters does the roller travel per hour?
压路机滚筒的直径是1.8m，如果它每分钟滚动20周，压路机每小时行多少米？
<gadget id="calculator">3.14 * 1.8 * 20 * 60</gadget>
<output>6_782.4</output>

<result>6_782.4</result>