A group of 23 or more people has a better than even chance that two people will share a birthday.

Yeah, thanks Marty, you're right of course, and that's what I really meant to say. In fact I originally had written along the lines of: "you could make money ... etc, etc." The person who first told me this, years ago, claimed to be well ahead of the game by using this in various pubs with an appropriate number of people present!

I'll follow your link gladly. The last time I tried to work it out to prove it to someone I got hopelessly lost in the process—at least I now know the number is 23!

Rgds, lusy