A minute hand is 2 cm long, what is the distance traveled by the tip of the needle in 30 minutes?
一根分针长2厘米，30分钟针尖所走过的路程是多少．
<gadget id="calculator">2 * 3.14 * 2</gadget>
<output>12.56</output>

<gadget id="calculator">12.56 / 2</gadget>
<output>6.28</output>

<result>6.28</result>