• 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.

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. .