The radius of the driving wheel of the train is 0.75 meters. If the driving wheel rotates 200 times per minute, how many kilometers can the train travel per hour?
火车主动轮的半径是0.75米，如果主动轮每分钟转200周，那么这列火车每小时可以行驶多少千米？
<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">2 * 3.14 * 0.75 * 200 * 1 * (3/50)</gadget>
<output>56.52</output>

<result>56.52</result>