On a map with a scale of 1:2000000, if the distance between A and B is 4.5 cm, what is the actual distance between A and B in kilometers?
在一幅比例尺为1：2000000的地图上，量得甲、乙两地的距离为4.5厘米，则甲、乙两地的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">4.5 / (1/2_000_000) / 100_000</gadget>
<output>90</output>

<result>90</result>