Roman Numerals

Write to_roman(n) converting an integer (1–3999) to a Roman numeral. Print the result for 4, 44, 1994 and 3999.

IV
XLIV
MCMXCIV
MMMCMXCIX

Walk a value→symbol table from largest to smallest, including the subtractive pairs (900 CM, 400 CD, 90 XC, 40 XL, 9 IX, 4 IV).

def to_roman(n):
    table = [(1000, "M"), (900, "CM"), (500, "D"), (400, "CD"),
             (100, "C"), (90, "XC"), (50, "L"), (40, "XL"),
             (10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I")]
    out = ""
    for value, symbol in table:
        while n >= value:
            out += symbol
            n -= value
    return out

for n in (4, 44, 1994, 3999):
    print(to_roman(n))

Run your code to check it…