The minute hand of a clock is 10 centimeters long, how many centimeters does the tip of the needle travel from the number "3" to the number "9".
一个钟表的分针长10厘米，它从数字"3"走到数字"9"，针尖走过了多少厘米．
<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<gadget id="calculator">6 / 12</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 * 3.14 * 10 * (1/2)</gadget>
<output>31.4</output>

<result>31.4</result>