You just purchased the new safe: It has a key pad with 26 letters on it.
a. If the code is 4 random letters, and no letter is employed more than once, how many different possible codes are there?
b. If the code is 4 random letters, and letters can be employed multiple times, how many different possible codes are there?
c. If no letter can be employed more than once. Does Order Matter?
d. If the manufacturer decided to make the more secure model which employs 5 letters (no repeats) how many codes are there then?
e. If letters can be employed multiple times and there're 5 letters, and the first letter should be an "A or B" how many different codes are available?