Convert numbers to Roman numbers

roman.py

import math

def digit(digits,num, n, upper, outlier, lower):
    multip = math.pow(10,n)
    
    if num >= multip:
        hundreds = int(num / multip)
        if hundreds == 9:
            digits.append(lower+upper)
            num -= (9 * multip)
        elif hundreds > 4:
            digits.append(outlier)
            num -= (5 * multip)
        elif hundreds == 4:
            digits.append(lower+outlier)
            num -= (4 * multip)
        for i in range(int(num/multip)):
            digits.append(lower)
            num-= multip
    return num, digits
                  
def intToRoman(num):
    
    digits = []
    
    thousands = int(num / 1000)
    if thousands > 0:
        [digits.append("M") for i in range(thousands)]
        num = num - (1000 * thousands)

    num, digits = digit(digits, num, 2, 'M', 'D','C')
    num, digits = digit(digits, num, 1, 'C', 'L','X')
    num, digits = digit(digits, num, 0, 'X', 'V','I')
    
    return "".join(digits)


print 554, intToRoman(554)
print 449, intToRoman(449)
print 1, intToRoman(1)
print 114, intToRoman(114)
print 1114, intToRoman(1114)
print 1914, intToRoman(1914)
print 1994, intToRoman(1994)
print 1984, intToRoman(1984)