Correct Answer - Option 1 : 9
Calculation
Numbers lying between 100 and 1000 will be three-digit numbers
Let the number be xyz
⇒ xyz = 100x + 10y + z
The sum of the digits = x + y + z
Subtracting the sum of the digits from the number we get,
(100x + 10y + z) - (x + y + z) = 99x + 9y
⇒ 9(11x + y) which is always divisible by 9