A segment line with a distance of 20cm on the picture, using a scale of 1:2000, what is the actual distance in kilometers?
图上距离为20cm的一条段线，采用1：2000的比例尺，则实际距离为多少千米？
<gadget id="calculator">1 / 2_000</gadget>
<output>1/2_000 = around 0.0005</output>

<gadget id="calculator">20 / (1/2_000) / 100_000</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>