Question: How many different 4-digit PINs can be formed using the digits 0-9 if digits cannot be repeated?
Options:
Correct Answer: 5040
Solution:
The first digit can be any of 10 digits, the second can be any of 9, the third can be any of 8, and the fourth can be any of 7. Total = 10 * 9 * 8 * 7 = 5040.