19. The integers from 1 to 99 are written in ascending order without spaces. The sequence of digits is then grouped into triples of digits:
$$
123456789101112 \ldots 979899 \rightarrow(123)(456)(789)(101)(112) \ldots(979)(899) .
$$

Which of the following is not one of the triples?
A (222)
B (434)
C (464)
D (777)
E (888)
19. D The two-digit integers start with the pair of triples (101), (112). If we continue to consider the triples in pairs, then the following pairs start with the integers $13,16,19$, etc. That is, they start with those integers that are 1 more than a multiple of 3 . All of $22,43,46$, and 88 have that form, they start the triples $(222),(434),(464)$ and (888). Although 76 also has that form, it starts the triples (767) followed by (778), so that 777 is not a triple.