Ohio license plates have 3 letters followed by 3 digits. There are 26 possible letters and 10 possible digits for each spot. Allowing repeats, there are 26^3 * 10^3 = 17,576,000 possible license plate combinations. Without repeats, there are 26*25*24 * 10*9*8 = 11,232,000 possible plates. Since repeats are usually allowed for license plates, the total number of possible plates is 17,576,000.