private static String constructRomanNumeral(int digit, String one, String five, String ten) {
        switch (digit) {
            case 1: return one;
            case 2: return one + one;
            case 3: return one + one + one;
            case 4: return one + five;
            case 5: return five;
            case 6: return five + one;
            case 7: return five + one + one;
            case 8: return five + one + one + one;
            case 9: return one + ten;
            default:
                return "";
        }
    }