On a map, the measured actual distance from Beijing to Tianjin is 4 cm. Given that the scale of this map is 1:3,000,000, what is the actual distance in kilometers from Beijing to Tianjin?
在一幅地图上，测得北京到天津的实际距离是4厘米．已知这幅地图的比例尺是1：3000000，北京到天津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 / (1/3_000_000) / 100_000</gadget>
<output>120</output>

<result>120</result>