The radius of a car tire is 0.5 meters. If the wheel rotates 300 times per minute on average, how many kilometers does the car travel per hour?
汽车轮胎的半径是0.5米，如果车轮平均每分钟转300周，汽车每小时行驶多少千米？
<gadget id="calculator">1 * 60 * 300</gadget>
<output>18_000</output>

<gadget id="calculator">18_000 / 1_000</gadget>
<output>18</output>

<gadget id="calculator">2 * 3.14 * 0.5 * 18</gadget>
<output>56.52</output>

<result>56.52</result>