I guess not. There’s no definite right way, because it has been done wrongly for centuries anyway. However, there is a standard which limits the use of subtractive notations. This is the reason why neither my or the previous posters suggestions are used.
Only 4,9,40,90,400 and 900 are written using subtraction in standard notation. Every other number must be written using only addition.
Shouldn’t that be MIIM?
I guess not. There’s no definite right way, because it has been done wrongly for centuries anyway. However, there is a standard which limits the use of subtractive notations. This is the reason why neither my or the previous posters suggestions are used.
Only 4,9,40,90,400 and 900 are written using subtraction in standard notation. Every other number must be written using only addition.