If the minute hand of a clock is 15 cm long, how many centimeters can the tip of the minute hand travel in half an hour?
一钟表的分针长15厘米，半小时分针的尖端能行多少厘米．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 15 * 1</gadget>
<output>47.1</output>

<result>47.1</result>