The number 400 is written as CD in Roman numerals.
Roman numerals use seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Numbers are formed by combining symbols and adding their values. When a smaller symbol appears before a larger one, it is subtracted (e.g., IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900).
To convert 400: start with the largest possible symbol and subtract its value, repeating until the remainder is zero. The result is CD.
| Number | Roman Numeral |
|---|---|
| 395 | CCCXCV |
| 396 | CCCXCVI |
| 397 | CCCXCVII |
| 398 | CCCXCVIII |
| 399 | CCCXCIX |
| 400 | CD |
| 401 | CDI |
| 402 | CDII |
| 403 | CDIII |
| 404 | CDIV |
| 405 | CDV |