In a wall clock, the minute hand is 10 cm long, how many centimeters does the tip of the hand travel in half an hour?
一个挂钟，分针长10厘米，半小时针尖走过多少厘米．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 2 * 5</gadget>
<output>31.4</output>

<result>31.4</result>