A website requires a 7-digit password. How many different passwords can be made using the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 if each number can only be used once?

A. 120

B. 70

C. 5,040

D. 604,800

Since order matters when making a password, this is a permutation.

There are 10 digits to chose from, so we'll start writing our equation like this:

10! / (10-r) !

It's a 7 digit password, so we'll write this:

10! / (10-7) !

And then solve:

10!/3!

3628800/6

604800

There are 604800 possible passwords, making D the correct answer