C (49,6) above is a combination formula! C(n，r)=A(n，r)/r！ Represents how many ways to choose r numbers from n numbers! Your formula of choosing 7 from 36 above is wrong. It is an arrangement, not a combination! Arrangement means that the numbers are not in the same order and the results are different. If you combine them, there is no need for order. As long as the numbers are correct! I don't usually buy lottery tickets, but there seems to be a lottery ticket, and you must buy and open it in the same order. For example, the lottery number is 23456, which means that the first one is 2 and the second one is 3 ... The first one on your lottery ticket must be 2 and the second one is 3, so 65432 doesn't count! Like a two-color ball, it is a combination! As long as it's 23456, whether it's 65432 or 34562 when you buy it!