Back to this feature now that I’m heavily researching my next book (third book in the Assassin’s Gambit series).
One thing I rarely see discussed in fantasy novels is number systems. It seems to be generally assumed that fantasy worlds share the number system we use in America today, but in the Middle Ages in western Europe, that wasn’t the number system actually in use. They were still using Roman numerals.
Roman numerals! Like the ones used to count Super Bowls. XXVII and whatnot. The Romans were advanced in a lot of ways, but let’s face it, their numeral system was bad. It lacked a zero. You can add and subtract in it with reasonable competence (LXVI + CXXII = ??), but multiplication and long division? I don’t know–pretty difficult. They had a system for fractions that was based on twelfths rather than tenths and which is to modern eyes absolutely insane!
The numbers we use today are Arabic. While medieval western Europe limped along with Roman numerals, mathematical advances were taking place in Persia and India, where they had our modern-day numeral system, including the zero (it is “ours” because we adopted it). Algebra would be invented in Persia around 830 AD. It comes from the word al-jabr.
Arabic numerals would eventually be adopted in western Europe, but not until around the 14th century–close to the end of the Middle Ages.