Vì 3A39B chia hết cho 2 và 5 thì B sẽ = 0
Ta có 3 + A + 3 + 9 + 0 = 15 + a
Vậy A = 3
vì 3A39B phải chia hết cho 2 và 5 =>B= 0
mà phải chia hết cho 9 => 3+A+3+9+0 = 15 +A chia hết cho 9
=> A = 3.
vậy A= 3 B = 0
Để số 3A39B chia hết cho 2,5,9
Thì bắt buộc B phải = 0
Còn A = 3
=> Ta có : 33390 chia hết cho 2,5,9
Để số 3A39B chia hết cho 2,5,9
Thì bắt buộc B phải = 0
Còn A = 3
Ta có : 33390 chia hết cho 2,5,9
Vì 3A39B chia hết cho 2 và 5 thì B sẽ = 0
Ta có 3 + A + 3 + 9 + 0 = 15 + a
Vậy A = 3
+ Do 3A39B chia hết cho 2 và 5 . Suy ra B = 0 . Suy ra 3A39B = 3A390.
+ Do 3A390 chia hết cho 9 . Suy ra ( 3 + A + 3 + 9 + 0 ) chia hết cho 9. Hay ( A +15 ) chia hết cho 9. (1). Và A < 10. (2)
Từ (1) ; (2) suy ra : A = 3
Vậy A = 3 ; B = 0. Ta có số 33390.
Do số đó chia hết cho cả 2 và 5 =>B=0
Để 3A390 chia hết cho 9 =>3+A+3+9 chi hết cho 9
=>A=3
33390 là đúng mình thi viiolympic toán có câu này mà
a=3 b=0 dung
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