NUMBER LOGIC / JD · 2026.10.19
Roman Numerals: Reading, Subtraction, and Common Errors
Recognize Roman numerals and learn what modern notation can—and cannot—express.
Seven key symbols
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1,000. Roman numerals are not positional in the decimal sense: the value depends on the ordering and combination of symbols.
Subtractive notation
IV means 4 and IX means 9; XL means 40 and XC means 90; CD means 400 and CM means 900. For example, 2026 is MMXXVI.
A few limits
Modern conventions normally avoid repeating V, L, or D and do not write arbitrary subtraction pairs. Traditional Roman numerals also do not have a standard digit for zero.
Check your answer
Try converting 49, 90, 444 and 1,999. Compare the results with the Roman-numeral display on the corresponding fact pages.
The calculations are mathematical facts. Interpretations attached to popular number symbolism are a separate, non-scientific subject.