Want to put together a secret code. The code consists of 2 different digits and 3 different English letters (26 options). How many different codes can be put together?
I tried to think of it this way: $$10*9*26*25*24=1,404,000$$
Because I first choose two digits and then three letters. The answer by the book is:
I understand why they did it, but I do not know what I'm missing to get answer similar to their own.
Thank you very much.