On a map with a scale of 1:250000, the distance between A and B is measured to be 16 cm. What is the actual distance between A and B in kilometers?
在一幅比例尺为1：250000的地图上，量得ab两地的距离是16厘米，则ab两地的实际距离是多少千米．
<gadget id="calculator">1 / 250_000</gadget>
<output>1/250_000 = around 0.000004</output>

<gadget id="calculator">16 / (1/250_000) / 100_000</gadget>
<output>40</output>

<result>40</result>