Although within the Roman Empire itself it was enforced a set of stricter rules that would have lead to the standardization of Roman numerals writing, in the last hundred years some rules were applied to eliminate confusion.
We concluded that there is a set of six rules to be remembered about Roman numerals.
Read them below, in order. Don't worry if you don't understand something right away. When you finish reading all the six rules, things will become clearer.
1) The first rule - the set of basic symbols in Roman writing
- 1 = I (one)
- 5 = V (five)
- 10 = X (ten)
- 50 = L (fifty)
- 100 = C (one hundred)
- 500 = D (five hundred)
- 1000 = M (one thousand)
- 5000 = (V) (five thousand) *
- 10,000 = (X) (ten thousand) *
- 50,000 = (L) (fifty thousand) *
- 100,000 = (C) (one hundred thousand ) *
- 500,000 = (D) (five hundred thousand) *
- 1,000,000 = (M) (one million) *
* The number was also written with a bar above or between two vertical bars, to indicate multiplying that number by 1,000. We prefer writing in brackets because it is more accessible to computer users and for avoiding any possible confusion with the symbol for one - I.
At first, the Romans did not use numbers higher than 3999, having no representation for numbers 5,000, 10,000, 50,000, 100,000, 500,000, 1,000,000. These were added later on and for them various different notations were used, not necessarily the ones above. Thus, initially, the maximum number that could be written with Roman numerals was: MMMCMXCIX (3999).