On a map with a scale of 1:500000, the measured distance between A and B is 4 cm. On another map with a scale of 1:400000, how many centimeters should the distance between A and B be drawn?
在比例尺是1：500000的地图上，测得甲、乙两地的距离是4厘米，在另一幅比例尺是1：400000的地图上，甲、乙两地的距离应画多少厘米．
<gadget id="calculator">1 / 500_000</gadget>
<output>1/500_000 = around 0.000002</output>

<gadget id="calculator">4 / (1/500_000)</gadget>
<output>2_000_000</output>

<gadget id="calculator">1 / 400_000</gadget>
<output>1/400_000 = around 0.000002</output>

<gadget id="calculator">2_000_000 * (1/400_000)</gadget>
<output>5</output>

<result>5</result>