Death rays from Mars made Tim May <tcmay@got.net> write:
There's a way to generate a number for any person which is unique. It is not shared by anyone else on the planet.
It's not guaranteed unique. First, the dollar you use may be a forgery (why forge a dollar? I don't know, maybe they're practicing on low-denomination notes which noone ever looks at closely so they can get the twenties and hundreds perfect. I have a vague memory of someone doing this with either US dollars or UK pound notes some time ago, motivated by the "noone would ever bother forging a dollar/pound, so it has to be genuine" mentality). In addition you'd have to specify "US dollar" rather than just "dollar" because, apart from the different serial number formats, some countries will reissue banknotes if the originals are damaged in printing, which leads to the possibility of two (legitimate) notes with the same serial number being in circulation if the original isn't destroyed as required (I have some of these replacement notes for now-defunct NZ dollar and two-dollar notes stashed away somewhere). Does the US Treasury issue replacement notes if the originals are damaged in printing, or does it just destroy the notes and leave it at that? Peter.