If x4y5z is exactly divisible by 9, then the least value of (x + y + z) is

We know that if sum of digits of a number is divisible by 9, then the number is divisible by 9.


Here,


x + 4 + y + 5 + z = multiple of 9


x + y + z + 9 = 0, 9, 18, ….


Hence,


x + y + z + 18 = 18


But x + y + z cannot be 0 because then x, y and z will have to be 0.
Since x is the first digit, it cannot be 0.
x + y + z + 18 = 27


x + y + z = 9


the least value of (x + y) is 9

7