A license plate is to have the following form: 4 letters followed by 4 numbers. How many different license plates can be made, assuming that letters and numbers can be reused?
If we assume your letters range from A to Z and your digits from 0 to 9, you have 26 possibilities per letter and 10 per digit. This gives you 26^4*10^4 which is roughly 4 billion and a half.
