Take a lottery group with a tail number of 0000 to 9999 * * * 10000. The suffixes are 8888, 0888, 1888, ... 9888 * * 9, with the suffix 8888 removed, and 0088, 0 1 88, ... 9988 * * with the suffix 88 removed.

So the bonus is 5000x1+500x9+20x90+2x900 =13100.

Lottery * * * Price 2x 10000=20000.

The reward rate of return is13100/20000 = 65.5%.

The service fee is 0.05x 10000=500.

The income of each lottery company is 20000-13100-500 = 6400.

So the yield is 6400/20000=32%.