Question 836323
The digits must add to some number that's a multiple of 9.


9+8+2+7+x+1+5+8+8


x+48


x + 45 + 3


(x+3) + 45


(x+3) + 9*5


So x+3 must be a multiple of 9. If x is a single digit number, then x must be 6 since x+3 = 6+3 = 9


So the largest value of x is 6.