Question

X is a number formed by writing the first 1002 natural numbers one after another from left to right then find the remainder when X is divided by 9 is___

Answer 1

Remainder when X is divided by 9, is same as the remainder when the sum of digits of X is divided by 9. Sum of the digits of first 999 natural numbers is 13500, which is divisible by 9.
Now, the sum of digits of 1000, 1001, 1002 is 1,2 and 3, respectively.
Sum of digits of X is 9n + (1+2 +3) =9n +6. So the required remainder is 6.