The minute hand of a wall clock is 20 cm long. What is the distance traveled by the tip of the minute hand after 30 minutes?
一只挂钟的分针长20cm，经过30分钟后，分针的尖端所走的路程是多少cm．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">2 * 3.14 * 10</gadget>
<output>62.8</output>

<result>62.8</result>