Question

What is least value should replaced by if in 231#231 so the number become divisible by 9

Answer 1

If 231#231 is divisible by 9,
then the total of the digits should be a multiple of 9.

Therefore, 2+3+1+2+3+1 = 12.
So to get 18 which is the next multiple of 9, 6 is needed.
The # is 6.