Sagot :
[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
7 again on the second because zero can be included.
- 7 7
6 for the third because repetition is not allowed
- 7 7 6
5 for the fourth because repetion is not allowed
- 7 7 6 5
4 for the fourth because repetion is not allowed
- 7 7 6 5 4
3 for the fourth because repetion is not allowed
- 7 7 6 5 4 3
2 for the fourth because repetion is not allowed
- 7 7 6 5 4 3 2
By fundamental counting principle: We will multiply all of the entries:
- 7×7×6×5×4×3×2 = 35,280 ways
[tex] \large\underline{ \bold{ANSWER}}[/tex]
[tex]\longmapsto\boxed{\textrm{P=35280 ways}}[/tex]