The distance between A and B is 400km, and the distance on a map is 40cm. The distance between B and C is 300km. What is the distance in centimeters on this map?
A，B两地相距400km，在一幅地图上的距离是40cm，B，C两地相距300km，在这幅地图上的距离是多少厘米．
<gadget id="calculator">400 * 100_000</gadget>
<output>40_000_000</output>

<gadget id="calculator">40 / 40_000_000</gadget>
<output>1/1_000_000 = around 0.000001</output>

<gadget id="calculator">300 * 100_000 * (1/1_000_000)</gadget>
<output>30</output>

<result>30</result>