The minute hand of a clock is 40 cm long, what is the distance traveled by its tip in 30 minutes?
一个时钟分针长40cm，它的尖端转动30分钟所走的路程是多少cm？
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">2 * 3.14 * 20</gadget>
<output>125.6</output>

<result>125.6</result>