Date: Dec 14, 1996 10:33 PM
Author: Sherman Stein
Subject: Roman arithmetic

I have recently been asked how the Romans computed with Roman numerals. I 
don't know the answer. Is there a good reference? My guess is that they
didn't. Instead they just used an abacus (the Britannica has a photo of
one from Roman times.) In any case there ought to be extant evidence,
since Arabic numerals weren't introduced before 1200.
Sherman Stein