MIX is a number used in the number system of ancient Rome, called Roman Numerals.We here at Research Maniacs think it's remarkable that Roman Numerals have stood the test of time and are still being used today.IX is a number used in the number system of ancient Rome, called Roman Numerals.We here at Research Maniacs think it's remarkable that Roman Numerals have stood the test of time and are still being used today.