[tex] \large\underline \bold{{SOLUTION}}[/tex]
[tex]\textrm{If repetition is not allowed}[/tex]
We can plug 7 numbers on the first digit: because zero is not included
7 again on the second because zero can be included.
6 for the third because repetition is not allowed
5 for the fourth because repetion is not allowed
4 for the fourth because repetion is not allowed
3 for the fourth because repetion is not allowed
2 for the fourth because repetion is not allowed
By fundamental counting principle: We will multiply all of the entries:
[tex] \large\underline{ \bold{ANSWER}}[/tex]
[tex]\longmapsto\boxed{\textrm{P=35280 ways}}[/tex]