How many different positive integers exist between 10^7 and 10^8, the sum of whose digits is equal to 2? Pick one:
A) 6  B) 7  C) 5  D) 8  E) 18

Rationale: so , the numbers should be from 10 , 000,000 to 100 , 000,000 the following two cases are possible for the sum of the digits to be 2 : 1 . two 1 ' s and the rest are 0 ' s : 10 , 000,001 10 , 000,010 10 , 000,100 10 , 001,000 10 , 010,000 10 , 100,000 11 , 000,000 7 numbers . 2 . one 2 and the rest are 0 ' s : 20 , 000,000 1 number . total = 8 numbers . answer : d
Answer: D