The access code for a car's security system consists of four digits, 0 through 9. Once a digit is used, it cannot be repeated. There are choices for the first digit, choices for the second digit, choices for the third digit, and choices for the fourth digit.

10 9 8 7

Step-by-step explanation:

There are 10 choices for the first digit,

9 choices for the second digit,

8 choices for the third digit, and

7 choices for the fourth digit.

Using the fundamental counting principle, how many access codes are possible? 5,040

If the digits 0 through 9 could be repeated, how many access codes would be possible? 10,000