Britsimon
Super Moderator
Butters explained well, but just to finish off. There are just under 65000 actual case numbers. That is one for each principal selectee and whatever number of derivatives they have. So - there are about 54000 derivatives on the 65K cases. As has been mentioned the holes theory (which is now a well established understanding) means the holes account for the difference between the 65K and the cumulative total number of case numbers in the 6 regions.Thanks! I didn't know about this holes theory, I think this was the piece that I was missing to have the puzzle completed.