Question 29
Let $k$ be a positive integer. Find the number of nonnegative integers $n$ less than or equal to $10^k$ satisfying the following conditions:
(i) $n$ is divisible by $3$;
(ii) Each decimal digit of $n$ is one of the digits $2$, $0$, $1$ or $7$.
(i) $n$ is divisible by $3$;
(ii) Each decimal digit of $n$ is one of the digits $2$, $0$, $1$ or $7$.