I'm a bit confused about this one problem in my Barrons SAT II Math book. It reads, "A code consists of two letters of the alphabet followed by 5 digits. How many such codes are possible?"
Barrons gives the answer as (26)(26)(10)(10)(10)(10)(10)= 67,600,000 possible codes. I am confused because I think this method would produce repeat answers, and I think I would have to divide it by something, but I'm not sure what. (I"m not sure how to describe how I am confused, I just feel like this method would produce for example aa54865 twice and not take into account that aa is the same no matter what order the a's are placed in... Am I making sense?) Anyways, is Barrons right or am I? And if I am right, what would I need to divide by to get the right answer?
Thank you very much!