What Does D Mean in Roman Numerals?
D is five hundred, a single letter for a large jump. It turns up inside years and long numerals as the hinge of the hundreds, the same way V hinges the units and L hinges the tens.
Where D comes from
D began as half of an older symbol for one thousand, split down the middle to stand for half of that value, five hundred. Once Roman writing settled on M for a thousand, the leftover half kept its meaning as D.
How D behaves
- D is never repeated. A thousand is M, not DD, so a second D never appears.
- D is never subtracted. It is always added, never placed before a larger symbol.
- D takes hundreds after it (DC, DCC, DCCC) and is reached past by the subtractive CM for nine hundred.
D in action
The same symbol behaves differently depending on what sits beside it. These worked examples show D added, and where it applies, subtracted.
| Number | Numeral | What D is doing |
|---|---|---|
| 500 | D | D on its own is five hundred. |
| 600 | DC | DC is five hundred plus one hundred. |
| 400 | CD | CD places a hundred before the D, the only time a symbol sits to its left. |
| 1,666 | MDCLXVI | MDCLXVI runs a thousand, five hundred, a hundred and the rest, using D once. |
Try it in the converter
Type any number to see where D lands inside its numeral, or read a numeral back to a number.
500 is written D in Roman numerals.
Frequently asked questions
What does D mean in Roman numerals?
D means five hundred. It is a single symbol for a value that would otherwise need five C strokes.
Why is a thousand not written DD?
Because a thousand has its own symbol, M. Roman numerals always use the larger single symbol where one exists, so two D's are never written.
Can D be subtracted?
No. Like V and L, D is always added. Only I, X and C are ever placed before a larger symbol to subtract.