The total length of the Jinzhong Reservoir Greenway is about 12 kilometers. It is drawn on a map with a scale of 1:400,000. What is the distance on the map?
金钟水库绿道全长约12千米，画在比例尺为1：400000的地图上，图上距离应是多少？
<gadget id="calculator">1 / 400_000</gadget>
<output>1/400_000 = around 0.000002</output>

<gadget id="calculator">12 * 100_000 * (1/400_000)</gadget>
<output>3</output>

<result>3</result>