Roman numerals both ways
Convert a number like 2026 into MMXXVI, or decode Roman numerals back to digits. Roman numerals use seven letters (I, V, X, L, C, D, M) with subtractive pairs like IV (4) and IX (9). They're standard for copyright years, book chapters, clock faces, Super Bowls and movie sequels.
Supports the classic range 1–3,999 that standard Roman numerals cover.