If n$\in$ N and 300 < n < 3000 and n is made of digits by taking from 0, 1, 2, 3, 4, 5 then greatest possible number of values of n is (repetition is allowed)

300<n<3000

No of 3 digit numbers formed = 3×6²-1

                3       ×     6     ×     6

No of 4 digit number (<3000)= 2×6²

            2                            6                            6                          6

No of permutations between 300 and 3000 $=3\left(6^2\right)+2\left(6^3\right)-1$

$$\begin{gathered} =108+432-1 \\ =539 \end{gathered}$$