Home Security A home security company offers a security system that uses the numbers 0 through 9, inclusive, for a 5-digit security code.
a. How many different security codes are possible?
b. If no digits can be repeated, how many security codes are available?
c. Suppose the homeowner does not want to use 0 as one of the digits and wants only two of the digits to be odd. How many codes can be formed if the digits can be repeated? If no repetitions are allowed, how many codes are available?