The distance between the two ports measured on a map with a scale of 1:3000000 is 4.2cm. How many kilometers is the actual distance between the two ports?
在比例尺为1：3000000的地图上量得两个港口间的距离是4.2cm，这两个港口之间的实际距离是多少千米？
<gadget id="calculator">1 / 3_000_000</gadget>
<output>1/3_000_000 = around 0</output>

<gadget id="calculator">4.2 / (1/3_000_000) / 100_000</gadget>
<output>126</output>

<result>126</result>