The minute hand of a clock is 1 decimeter long, from 6:30 to 10:30, how many decimeters does the tip of the minute hand travel.
一个钟的分针长1分米，从6：30到10：30，分针的针尖走过多少分米．
<gadget id="calculator">2 * 3.14 * 1</gadget>
<output>6.28</output>

<gadget id="calculator">6.28 * 4</gadget>
<output>25.12</output>

<result>25.12</result>