Question

A computer password is required to be 9 characters long. How many passwords are possible if thepassword requires 3 letter(s) followed by 6 digits (numbers 0-9), where no repetition of any letter or digitis allowed? There are _______ possible passwords

Answer 1

Since the alphabet has 26 letters and the digits are 10, and where no repetition of any letter or digit is allowed, using the multiplication principle we have:

26 25 24 10 9 8 7 6 5 = 2.36 x 10^9 possible passwords, multiplying

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