The actual distance from A to B is 800 kilometers. On a map with a scale of 1:4,000,000, what is the distance from A to B?
甲地到乙地的实际距离是800千米，在一张比例尺是1：4000000的地图上，甲地到乙地的距离是多少？
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">800 * 100_000 * (1/4_000_000)</gadget>
<output>20</output>

<result>20</result>