How many 4 digits? How many odd numbers? How many even numbers?

How many 4 digits? How many odd numbers? How many even numbers?

Can these six numbers be reused? (for example, 1000) if not, the one upstairs is wrong
The answer that cannot be repeated is as follows:
It means four digits
The total number of four digits can be composed as follows: the first box can have six cases (1-6), the second box can have six cases (the number left), the third box can have five cases (the number left), and the fourth box can have four cases (the number left). That is, the number of four digits n = 6 × 6 × 5 × 4 = 720
The number of odd numbers: ① when the thousand digits are even, there are 3 × 3 × 5 × 4 = 180
② When the thousand digits are odd, there are 3 × 2 × 5 × 4 = 120
Therefore, there are odd N1 = 180 + 120 = 300
Even number N2 = 720-300 = 420