Easy probability question
Postal codes have the form LDL DLD (where L is any letter from A-Z and D is any digit from 0-9). Suppose a computer program generates postal codes randomly in such a way that no two generated postal codes are dependent on each other. What is the probability that the program will generate the same postal code two times in row?
I figured that there were 17,576,000 different codes. So I thought the probability of getting the same one twice was 2/17,576,000, however the answer shows 1/17,576,000.
Can anyone explain why the numerator is just 1? Thanks for the help!