On a map with a scale of 1:4,000,000, the distance from Beijing to Xi'an is 30cm. What is the actual distance in kilometers between the two places?
在比例尺1：4000000的地图上，量得北京到西安的距离是30cm．求两地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">30 / (1/4_000_000) / 100_000</gadget>
<output>1_200</output>

<result>1_200</result>