How to multiply, Roman-numeral style. A Different Kind of Multiplication
It is often said that an important advantage of the decimal notation over the Roman one is that makes multiplication of numbers much easier. Adding CLXXVII to XXIII may be relatively straightforward–but how about multiplying the two?
4 in Roman numerals is IV, not IIII.
If you read the article, they note that “IV” was a convention adopted in the middle ages.