Question
Each Student at a certain university is given a 6-digit code (such as 123789 or 001122)
(a) how many different codes are there?
(b) how many codes read the same forward and backward?
(c) how many codes contain only odd digits?
(d) how many codes contain at least one even digit?
(a) how many different codes are there?
(b) how many codes read the same forward and backward?
(c) how many codes contain only odd digits?
(d) how many codes contain at least one even digit?