Divisibility rule of 3 is: if the sum of digits of a number is divisible by 3, then the number is also divisible by 3. Now, 8 + 7 + x + 3 + 9 + 2 + x + 0 + 1 = 30 + 2x substitute x= 9 30 + 2 × 9 = 30 + 18 = 36 divisible by 9 Hence, the largest possible value of x = 9.