The set of Roman numerals used for writing calendar dates
Numerals between 1 and 1,000:
- I = 1 (one); V = 5 (five); X = 10 (ten); L = 50 (fifty); C = 100 (one hundred); D = 500 (five hundred); M = 1,000 (one thousand);
For writing dates in the future:
- (*) V = 5,000 or |V| = 5,000 (five thousand); see below why we prefer: (V) = 5,000.
- (*) X = 10,000 or |X| = 10,000 (ten thousand); see below why we prefer: (X) = 10,000.
Notes:
- Note 1: (*) These numbers were written either with an overline (a bar above the number) or between two vertical lines (two vertical bars).
- Note 2: (*) Instead we prefer to write these larger numerals between brackets "()" since: 1) when compared to the overline - it is more accessible to computer users; 2) when compared to the vertical line - it avoids any confusion between the vertical line "|" and the Roman numeral "I" (one).
- So, (V) = 5,000 and (X) = 10,000.
- Note 3: (*) Romans were not using right from the beginning numbers larger than 3,999, so they initially had no representation for numbers like:
- 5,000 = (V), 10,000 = (X), 50,000 = (L), 100,000 = (C), 500,000 = (D), or 1,000,000 = (M).
- These larger numerals were added later to the system and various different notations were used for them, not necessarily the ones above.
- For a long time, the maximum number that could be written using Roman numerals was:
- MMMCMXCIX = 3,999.