The scale of a map is (1/15000000). The total length of the Yangtze River in my country is 42cm measured on this map. What is the actual length of the Yangtze River in km?
一幅地图的比例尺是(1/15000000)，在这幅地图上量得我国长江的全长是42cm，长江的实际全长是多少km．
<gadget id="calculator">1 / 15_000_000</gadget>
<output>1/15_000_000 = around 0</output>

<gadget id="calculator">42 / (1/15_000_000) / 100_000</gadget>
<output>6_300</output>

<result>6_300</result>