On a map with a scale of 1:5,000,000, the distance from Nanjing to Beijing is measured to be 18 centimeters. A train travels 90 kilometers per hour. How long does it take for this train to travel from Nanjing to Beijing?
在一幅比例尺是1：5000000的地图上，量得南京到北京的距离是18厘米，一列火车每小时行驶90千米，这列火车从南京到北京需要多少小时？
<gadget id="calculator">1 / 5_000_000</gadget>
<output>1/5_000_000 = around 0</output>

<gadget id="calculator">18 / (1/5_000_000) / 100_000 / 90</gadget>
<output>10</output>

<result>10</result>