In an alarm clock, the minute hand is 3 cm long, how many cm does the tip of the minute hand travel in 1 hour.
一个闹钟，分针长3cm，1小时分针尖端走过多少cm．
<gadget id="calculator">3.14 * 2 * 3</gadget>
<output>18.84</output>

<result>18.84</result>