Geraldine is picking a four-digit password by using the digits 0 through 9. She can use each digit only once. How many different passwords are possible?

Question

asked Apr 28, 2017 42.1k views

2 Answers

Navin Viswanath · Answer 1 · 2017-05-02T01:21:15+0000

The number of different passwords possible are:

5040

It is given that:

Geraldine is picking a four-digit password by using the digits 0 through 9.

Also she has to use each digit just once.

Hence, the number of such passwords possible are:

10×9×8×7=5040

( Since for the first place we have 10 choices as any of the digit 0-9 could come.

Also, for the second place we will have 9 choices as the number which came at the first place can't be placed again at the second.

Similarly for the third place we have 8 choices as the number which came in the first and second place is not be repeated

and for the fourth place any of the remaining 7 numbers could come up)