The whole numbers from 1 to 1000 are written. How many of these numbers have at least two 7's appearing side-by-side?
(A) 10
(B) 11
(C) 21
(D) 30
(E) 19
The positive whole numbers less than 1000 that end with 77 are $77,177,277,377,477,577$, $677,777,877,977$.

The positive whole numbers less than 1000 which begin with 77 are $77,770,771,772,773,774$, $775,776,777,778,779$.

There is no other way for a positive whole number less than 1000 to contain at least two 7's side-by-side.

There are 10 numbers in the first list and 11 numbers in the second list. Since 2 numbers appear in both lists, the total number of whole numbers in the two lists is $10+11-2=19$.

ANSWER: (E)