Question

The decimal d is formed by writing in succession all the positive integers in increasing order after the decimal point; that is, d = 0.123456789101112 . . . . What is the 100th digit of d to the right of the decimal point?

(A) 1
(B) 0
(C) 5
(D) 8
(E) 9

Answer 1

C. 5.

Explanation:

There are 9 1 digit numbers, then from 10 to 19 we have another 20 digits

then 20 to 29 is another 20 digits.

29 digits give 9 of 19

49 digits give 9 of 29

69 digits give 9 of 39

89 digits give 9 of 49

99 digits give 4 of 54

100 digits give 5.