The diameter of the locomotive driving wheel of a train is 1.5 meters. When the train is running, the drive wheel rotates an average of 300 times per minute. Approximately how many kilometers per hour does the train travel?
一列火车的机车主动轮的直径是1.5米．火车运行时，主动轮平均每分转300圈．这列火车每小时大约行驶多少千米？
<gadget id="calculator">1 * 1_000</gadget>
<output>1_000</output>

<gadget id="calculator">60 / 1_000</gadget>
<output>3/50 = around 0.06</output>

<gadget id="calculator">3.14 * 1.5 * 300 * 1 * (3/50)</gadget>
<output>84.78</output>

<result>84.78</result>