function convert(num) {
  var numerals = [[1000, 'M'], [900, 'CM'], [800, 'DCCC'], [700, 'DCC'], [600, 'DC'], [500, 'D'], [400, 'CD'], [300, 'CCC'], [200, 'CC'], [100, 'C'], [90, 'XC'], [80, 'LXXX'], [70, 'LXX'], [60, 'LX'], [50, 'L'], [40, 'XL'], [30, 'XXX'], [20, 'XX'], [10, 'X'], [9, 'IX'], [8, 'VIII'], [7, 'VII'], [6, 'VI'], [5, 'V'], [4, 'IV'], [3, 'III'], [2, 'II'], [1, 'I']];
  var numAsNumerals = '';
  var i = 0;
  while (i < numerals.length) {
    if (num >= numerals[i][0]) {
      numAsNumerals = numAsNumerals.concat(numerals[i][1]);
      num -= numerals[i][0];
    }
    else {
      i++;
    }
  }

 return numAsNumerals;
}

convert(36);