To check the divisibility of a number by 11, the rule is to find the difference between the sum of the digits at odd places (from the right) and the sum of the digits at even places (from the right) of the number. If the difference is either 0 or divisible by 11, then the number is divisible by 11.
3 + 9 = 12, A + 8
A + 8 - 12 = 0
A - 4 = 0 or A - 4 = 11
A = 4 or A= 15, A = 15 is not possible.
So, the number is 3498.