On a map with a scale of 1:4000000, the length of the road between A and B is measured to be 9cm. A car travels 90 km per hour, how many hours does it take to drive from point A to point B?
在比例尺为1：4000000的地图上，量得甲乙两地公路长9cm．汽车每小时行90km，从甲地开往乙地需要多少小时？
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">9 / (1/4_000_000) / 100_000 / 90</gadget>
<output>4</output>

<result>4</result>