Question

A website requires a four-digit numerical password in which the digits cannot repeat. How many possible passwords are there?
24
5,040
151,200
3,628,800

Answer 1

10!=3628800

Answer 2

We have 4 positions
\[\large ----\]
We have digits 0-9, total 10 digits

Answer 3

10x9x8x7x6x5x4x3x2x1

Answer 4

First position can be filled in 10 ways
after choosing one no., we have 9 digits for the second place and similarly 8 for the third and 7 for the fourth
\[\huge10 \times 9 \times 8 \times 7=5040\]

Answer 5

oh yea

Answer 6

@Lunalovegood do you understand?

Answer 7

yes

Answer 8

Good:)