设计一个出租车计费系统：

起步价为5元（2km以内），2km后，0.8元/0.5km 要求每500m刷新计费一次，在8位数码管中，前四位显示数码管显示里程数,后四位数码管显示价钱（角，元，十元，百元）

-Billing system to design a taxi: Pricing starts at 5 yuan (2km or less), 2km after the 0.8 yuan/0.5km　billing refresh every 500m time, in the 8-bit digital tube, the former four digital display shows mileage the number after the price of four digital tube display (Kok, Yuen, eleven million dollars)