From the complex abacus the romans left us, it would seem that they used both base 10 and base 12 (for fractions - 360° in a circle is an extension of that). Ba

From the complex abacus the romans left us, it would seem that they used both base 10 and base 12 (for fractions - 360° in a circle is an extension of that). Base 12 seems to be slightly better than 10, but switching over would be WAY harder to "finishing" algebra... (and we wouldn't have the quite important these days 10^3~2^10 approximation.)