3.c) The combination to Mike's hotel safe has five digits, and each digit can be any number from O to 9. Mike can set the combination himself, but he doesn't like the number 6 so he refuses
to use that number in his combination. How many different combinations to his safe could
Mike set
(0) if digits can be repeated,
if repetition of digits is not allowed?
(iii) if repetition is allowed, and Mike wants his combination to be an even number?