Over many years, I asked several people about this but never got a satisfactory answer. My puzzlement comes from the fact that *modern* Latin writes/pronounces numbers in essentially decimal/positional ways. I think it was Tony Hoare (who read “Greats” at Oxford) who wondered whether the “normal” Roman numerals used a lot of straight lines because they were carved into stone!? I’d be very interested if you get a solid explanation of how calculations were done cliff jones On 2019-02-20, at 20:36, herbert.bruderer@bluewin.ch<mailto:herbert.bruderer@bluewin.ch> wrote: How did the Romans calculate? https://cacm.acm.org/blogs/blog-cacm/234881-how-did-the-romans-calculate/ful... Hi all: Does anyone know how the Romans calculated with the Roman numeral system? What is the meaning of the right-most slot of the Roman hand abacus? Do you have Roman hand abaci (original devices or replicas) in your collection? Thank you very much for your help. Best wishes, Herbert Bruderer _______________________________________________ This email is relayed from members at sigcis.org<http://sigcis.org>, the email discussion list of SHOT SIGCIS. Opinions expressed here are those of the member posting and are not reviewed, edited, or endorsed by SIGCIS. The list archives are at http://lists.sigcis.org/pipermail/members-sigcis.org/ and you can change your subscription options at http://lists.sigcis.org/listinfo.cgi/members-sigcis.org