I believe this is what he means. the ones digit for 9^1, 9^2 ... 9^8, follows a pattern of 1, 9 , 1, 9 ... . if you add up an even amount (8 in this case) of odd digits, you will get an even digit. an even digit that is divisible by 3 should also be divisible by six, because it will have a factor of...