ROMAN(number[,type])
ROMAN function returns an arabic number in the roman numeral style, as text. number is the number you want to convert and type is the type of roman numeral you want.
ROMAN(999) equals CMXCIX.
ROMAN(999,1) equals LMVLIV.
ROMAN(999,2) equals XMIX.
ROMAN(999,3) equals VMIV.
ROMAN(999,4) equals IM.