Question

computer password is required to be 5 characters long. How many passwords are possible if the password requires 1 letter(s) followed by 4 digits (numbers 0-9), where no repetition of any letter or digit is allowed

Answer 1

131,040 passwords

Explanation:

For the letter we have 26 options (The alphabet).

For the first digit, we have 10 options (0, 1, 2, 3, 4, 5, 6, 7, 8, or 9).

For the second digit, we have 9 options left.

For the third digit we have 8 options left.

For the final digit, we have 7 options left.

26 x 10 x 9 x 8 x 7 = 131,040