This problem is more complicated than you have considered.

If the number should begin with 2 then the second digit must be 5, 6, or 7.

The last two digits can be . That gives 60 numbers begin with 2.

If the first digit is 6, then the second digit can be 2, 3, or 4. SO?

If the first digit is 3, 4, or 5, then the next three can be . SO?