2 centimeters on the map means the actual distance is 40 kilometers, and the distance between A and B is 90 kilometers, how many centimeters should be drawn on this map.
图上2厘米表示实际距离40千米，甲、乙两地相距90千米，在这幅地图上应该画多少厘米．
<gadget id="calculator">40 * 100_000</gadget>
<output>4_000_000</output>

<gadget id="calculator">2 / 4_000_000</gadget>
<output>1/2_000_000 = around 0</output>

<gadget id="calculator">9_000_000 * (1/2_000_000)</gadget>
<output>9/2 = around 4.5</output>

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