The Excel ROMAN function converts an arabic number to Roman. I.e. for a supplied integer, the function returns a text string depicting the roman numeral form of the number.
Syntax: =ROMAN (number, [form])
The ROMAN function syntax has the following arguments:
 Number Required. The Arabic numeral you want converted.

Form Optional. A number specifying the type of roman numeral you want. The roman numeral style ranges from Classic to Simplified, becoming more concise as the value of form increases. If supplied, this must have one of the following values:

Value Explanation Classic (default) 1 More concise 2 More concise 3 More concise 4 Simplified TRUE Classic FALSE Simplified
If the [form] argument is omitted, it takes on the default value of 0 (denoting the classic form is used).
Example: Let’s look at some Excel ROMAN function examples and explore how to use the ROMAN function as a worksheet function in Microsoft Excel:
Syntax: =ROMAN(A2,0)
Result:
Based on the Excel spreadsheet above, the following ROMAN examples would return:
Syntax: =ROMAN(A3,1)
Result: LMVLIV
Syntax: =ROMAN(A4,2)
Result: XMIX
Syntax: =ROMAN(A5,3)
Result: VMIV
Syntax: =ROMAN(A6,4)
Result: IM
Syntax: =ROMAN(A7)
Result: VI
Syntax: =ROMAN(A8)
Result: III
Syntax: =ROMAN(A9)
Result: IX
Syntax: =ROMAN(A10)
Result: XII
Syntax: =ROMAN(A11)
Result: XV
Syntax: =ROMAN(A12)
Result: CXXV
Syntax: =ROMAN(A13)
Result: CCXXVIII
Syntax: =ROMAN(A14)
Result: CCCXC
Syntax: =ROMAN(A15)
Result: MDCCCLV
Note:
 Number must be positive and less than the value 3999.
 The ROMAN function does the opposite of the ARABIC function
 The form argument controls whether the roman numeral is abbreviated or not. The argument is optional and the default is zero (classic nonabbreviated). The ROMAN function supports additional forms 14 which are progressively more concise.
 Note that if any of the arguments are input as decimal values, they are truncated to integers.
 #VALUE! – Occurs if either: The supplied number is < 0 or > 3999, or is nonnumeric; or the supplied [form] argument is supplied but is invalid (i.e. is not one of the values 0, 1, 2, 3 4, TRUE or FALSE).
 Roman numerals are represented by combinations of letters
 I = 1
 V = 5
 X = 10
 L = 50
 C = 100
 D = 500
 M = 1000