US bank customers select their own 3 digit PIN for use at ATMs. Assuming that the first digit cannot be zero, compute the number of possible outcomes when the digits can be repeated. And possible...

US bank customers select their own 3 digit PIN for use at ATMs. Assuming that the first digit cannot be zero, compute the number of possible outcomes when the digits can be repeated. And possible outcomes when the digits cant be repeated. If zero can be the first digit and numbers can be repeated, what is the probability that customer A and B select the same PIN?