On a map with a scale of 1:150,000, 3 cm represents the actual distance in kilometers.
在比例尺是1：150000的地图上，3厘米表示实际距离多少千米．
<gadget id="calculator">1 / 150_000</gadget>
<output>1/150_000 = around 0.000007</output>

<gadget id="calculator">3 / (1/150_000) / 100_000</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>