Create a function taking a positive integer as its parameter and returning a string containing the Roman Numeral representation of that integer.
Modern Roman numerals are written by expressing each digit separately starting with the left most digit and skipping any digit with a value of zero. In Roman numerals 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC. 2008 is written as 2000=MM, 8=VIII; or MMVIII. 1666 uses each Roman symbol in descending order: MDCLXVI.
Symbol-Value I-1 V-5 X-10 L-50 C-100 D-500 M-1,000
Remember that there can’t be more than 3 identical symbols in a row.
Because 4 and 9 in Roman numerals were unique cases, 4 and 9 in all digits were grouped separately and applied to the arrangement. The rest is the same as the algorithm for digits.