Gubaiyou Double Color Ball Method: In the first method of the Double Color Ball, if including the blue ball, the total number of differences will not exceed 21. When all the differences are distinct, D(t) reaches its maximum value of 21, and the maximum AC value is 21-(7-1)=15. If the blue ball is not included, there can be up to 15 differences. When all differences are distinct, D(t) reaches its maximum value of 15, and the maximum AC value is 15-(6-1)=10. In the second method, if including the blue ball, then r=7 (i.e., the betting result contains 7 numbers), and one betting result is 01 15 20 21 22 30 12.