The Curta.org Bulletin Board

[michm_de]

I often wonder who “invented” the idea that prime number Curtas are such special collectibles? Does this special area of interest have a history? Who could give me some background information? I am a collector of calculating machines (to document the history of mechanical computing) but I never came across the idea to give prime serial numbers a special focus except for Curtas. Furthermore I wonder if for a Curta type II the whole six digit number has to be considered for a prime number analysis or if the actual production number is the relevant integer, i.e. omitting the highest digit “5” which is the type II indication? Thank you for an answer.

[curtafan]

For a prime # Curta you have to consider the whole 6 digit serial # like you see in this ebay auction of a rare twin prime Curta II:

http://cgi.ebay.de/very-rare-CURTA-II-Calculator-with-TWIN-PRIME-SERIAL_W0QQitemZ250221528135QQihZ015QQcategoryZ414QQssPageNameZWDVWQQrdZ1QQcmdZViewItem