1992 AHSME Problems/Problem 17

The 2-digit integers from 19 to 92 are written consecutively to form the integer $N=192021\cdots9192$ . Suppose that $3^k$ is the highest power of 3 that is a factor of $N$ . What is $k$ ? These problems are copyrighted © by the Mathematical Association of America, as part of the American Mathematics Competitions.