The diameter of the locomotive driving wheel of a train is 1.5 meters. If it rotates 300 times per minute on average, how many kilometers does the train travel per hour?
一列火车的机车主动轮的直径是1.5米，如果平均每分钟转300周，这列火车每小时行多少千米？
<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>