On a map with a scale of 1:2000000, the length of the railway between the two cities is measured to be 40 cm. What is the actual length of the railway in kilometers?
在比例尺是1：2000000的地图上，量得两个城市之间的铁路长是40厘米．这条铁路的实际长度是多少千米？
<gadget id="calculator">1 / 2_000_000</gadget>
<output>1/2_000_000 = around 0</output>

<gadget id="calculator">40 / (1/2_000_000) / 100_000</gadget>
<output>800</output>

<result>800</result>