Question 3
Let $K$ be a positive integer. Find the number of natural numbers $n\le10^K$ satisfying both:
i) $n$ is divisible by 3;
ii) every digit of its decimal representation belongs to $\{2,0,1,5\}$.
i) $n$ is divisible by 3;
ii) every digit of its decimal representation belongs to $\{2,0,1,5\}$.