function decimalToRoman(value) {
        for (var index = 0; index < romanNumerals.length; index++) {
            const numeral = romanNumerals[index];
            if (value >= numeral[0]) {
                return numeral[1] + decimalToRoman(value - numeral[0]);
            }
        }
        return '';
    }
converts a number to roman numerals
@param {number} value - the number
@returns {string} - the number in roman numerals