On a map with a scale of 1:4000000, the length of the road between A and B is measured to be 4.5 cm. What is the actual distance in kilometers between the two places?
在比例尺是1：4000000的地图上，量得甲、乙两地间的公路长4.5厘米，两地之间的实际距离是多少千米．
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">4.5 / (1/4_000_000) / 100_000</gadget>
<output>180</output>

<result>180</result>