Converts a whole number to roman numberals.

whole_number_to_roman_numerals.py

import sys


def main():
    roman_numerals = {
        0: '', 1: 'I', 2: 'II', 3: 'III', 4: 'IV', 5: 'V',
        6: 'VI', 7: 'VII', 8: 'VIII', 9: 'IX',
        10: 'X', 20: 'XX', 30: 'XXX', 40: 'XL', 50: 'L',
        60: 'LX', 70: 'LXX', 80: 'LXXX', 90: 'XC',
        100: 'C', 200: 'CC', 300: 'CCC', 400: 'CD', 500: 'D',
        600: 'DC', 700: 'DCC', 800: 'DCCC', 900: 'CM',
        1000: 'M'
    }

    multiple = 0
    roman_numeral_repr = ''
    whole_number = int(input('Enter a number: '))

    if whole_number >= 4000:
        print('Cannot convert numbers greater than 4000... for now. We need to use a line above letter.')
        sys.exit(1)

    while whole_number != 0:
        digit = (whole_number % 10) * (10 ** multiple)

        if (digit >= 1000):
            letter_occurences = digit / 1000
            roman_numeral = str(roman_numerals[1000]) * letter_occurences
        else:
            roman_numeral = str(roman_numerals[digit])

        roman_numeral_repr = roman_numeral + roman_numeral_repr

        whole_number //= 10
        multiple += 1

    print('Roman Numeral: {}'.format(roman_numeral_repr))


if __name__ == '__main__':
    main()