The radius of the driving wheel of the train is 0.75 meters. If it rotates 300 times per minute, how many meters can it do per hour?
火车主动轮的半径是0.75米，如果每分钟转300周，每小时可行多少米？
<gadget id="calculator">0.75 * 2</gadget>
<output>1.5</output>

<gadget id="calculator">3.14 * 1.5 * 300 * 60</gadget>
<output>84_780</output>

<result>84_780</result>