September 2013
Problem of the Month

Computer Passwords

In a recent issue, Consumer Reports recommended strong passwords for your accounts on the computer, making them as long as possible.

The longest passwords allowed on most unix based machines is 8 characters; some electronic devices allow only a four digit password (using the ten Arabic numerals).   Repetition of the same character is allowed in passwords but is not advised.

(1) How many different passwords are possible for a password allowing only 4 digits and repetition (where the four digits must be chosen from 0 to 9)?

(2) Choosing from all 95 ASCII Printable Characters (A through Z, a through z, 0 through 9, and other symbols like !, @, #, $, %, ^, &, *, etc), how many passwords are possible for a 4 character password?

(3) Using the same 95 ASCII printable characters in #2, how many different passwords are possible for an 8 character password?

Solution to the Problem:

(1) 10⁴ or 10,000

(2) 95⁴ or 81,450,625

(3) 95⁸ or 6,634,204,312,890,625 (over 6 quadrillion)

Correctly solved by:

1. James Alarie	Flint, Michigan
2. Chad Fore	Gate City, Virginia
3. Chase Smith	Mountain View High School, Mountain View, Wyoming
4. Caleb Flake	Mountain View High School, Mountain View, Wyoming
5. Cade Covington	Mountain View High School, Mountain View, Wyoming
6. Trystin Walker	Mountain View High School, Mountain View, Wyoming
7. Jake Snow	Mountain View High School, Mountain View, Wyoming
8. Levi Hanney	Mountain View High School, Mountain View, Wyoming
9. Ethan Salsbury	Mountain View High School, Mountain View, Wyoming

Send any comments or questions to: David Pleacher