Originally Posted by
cordelli
It's probably considerably less than that, very few of the early alphabet sequences (say A to M) are still on the road, people have long since got rid of them, so all you see are later combinations.
Once dealers started issuing plates it was much easier to just get new plates than transfer your old one when buying a car, so here we currently have way more plates starting with W, X, Y and Z than we do A, B, C, and D.
Once they get to 999 ZZZ they will go to 00 AA 00 so airport codes won't be seen for a very long time again.
Yes, I was assuming a random distribution of both license plates and airport codes. But the fact that WXYZ plates may outnumber ABCD plates would only decrease the odds if ABCD airports outnumber WXYZ ones.
If the license plate has 3 letters followed by 3 digits, the number of possibilities is 26 x 26 x 26 x 10 x 10 x 10 = 17,576,000, but if it is 3 letters and 3 digits in any order you multiply by 6! = 720 so the total now exceeds 12,000,000,000.
Well, of course the order matters, or your next flight to San Diego could land in the Bahamas.
