I bought my car in approximately September 2002. Its License Plate begins 4ZIX. I started looking at the structure of California's Licence plates, and saw that shortly afterwards, license plates started having the structure 5[A-Z][A-Z][A-Z][0-9][0-9][0-9] . ie the Five Series.
In approximately September of 2007, the Six Series started. This means that a series of numbers last about 5 years. I got to wondering if I could reconcile this with new registrations in California.
Here's some math.
A series has at most 26*26*26*10*10*10 = 17,576,000 possible licence plates.
Now, I would guess that certain three letter sequences are not used. eg TIT, ASS, SEX
and because 5 can look like an S, we have to exclude naughty words that begin an S - eg 5HIT
But these exclusions just remove a 1000 license plates at a time, so not significant. So - does this reconcile with the number of vehicles registered in California?
Whatever comes to mind, and then the interesting directions that thought will take you on the web.