72. a is a positive number. The unit digit of 2 9 aa a +++  cannot be?(A) 6(B) 5(C) 4(D) 312

問題詳情

72. a is a positive number. The unit digit of 2 9 aa a +++  cannot be?
(A) 6
(B) 5
(C) 4
(D) 312