A clock that runs accurately, the minute hand is 10cm long, how many πcm does the tip of the minute hand travel from 2 o'clock to 4 o'clock
一个走得精准的钟表，分针长10cm，当时针从2时走到4时，分针的尖端走过了多少πcm
<gadget id="calculator">10 * 2 * 2</gadget>
<output>40</output>

<result>40</result>