Measured on a map with a scale of 1:2000000, the length of the railway between A and B is 4cm. What is the actual distance from A to B in kilometers?
在比例尺为1：2000000地图上量得甲乙两地铁路长是4cm，甲地到乙地实际距离是多少千米．
<gadget id="calculator">1 / 2_000_000</gadget>
<output>1/2_000_000 = around 0</output>

<gadget id="calculator">4 / (1/2_000_000) / 100_000</gadget>
<output>80</output>

<result>80</result>