Roman Numeral Converter

Deciphering historical inscriptions and formal publication dates frequently presents a challenge due to the archaic rules of Roman numeration. Modern society still incorporates Roman numerals in monument cornerstones, film copyright notices, championship game titles, and classic timepiece dials. Translating between positional Arabic numerals and additive-subtractive Latin letters requires meticulous attention to symbol placement and subtraction pairs. You choose whether to convert an Arabic integer into Roman letters or transcribe an existing Roman string into a conventional number.

The converter processes the standard seven Latin characters—I, V, X, L, C, D, and M—and generates the corresponding equivalent in the target format. When reading or creating these notations, note that standard classical formatting is strictly defined for positive integers up to 3999 (MMMCMXCIX). The traditional Roman system does not include a character for zero, does not accommodate negative numbers, and cannot express fractional values without specialized non-standard symbols.

Integer-to-Roman conversion repeatedly matches and deducts descending decimal values from 1000 (M) down to 1 (I), inserting standard subtractive combinations such as CM, CD, XC, XL, IX, and IV where appropriate. Parsing Roman strings evaluates characters sequentially from left to right, subtracting a symbol's value when followed by a larger denomination and adding it otherwise. The algorithm operates strictly within the canonical 1 to 3999 range.