How many different license plates could be made if they have one or two letters followed by 1, 2, or 3 digits? Repetitions are allowed.
letters and numbers
(52+26)(1+10+100+1000).
the 52 represents two letters
the 26 represents one letter
the 1 represents no number
the 10 represents one number
the 100 represents two numbers
the 1000 represents three numbers.