Question

how many non-negative integers less than 10000 are there such that the sum of the digits of the numbers is divisible by 3

Answer 1

given that,
  sum is divisible by 3 means number is divisible by 3
 no 3 multiples in 1 to 10000 is the required answer
 3,6,9......................................9999
 so no of numbers is [10000/3]
                              =3333