The Excel ROMAN function converts an arabic number to Roman  i.e. for a supplied number, the function returns a text string depicting the roman numeral form of the number.
The format of the function is :
Where the arguments are as follows :
number    The number that is to be converted to a Roman numeral (must be an integer between 0 and 1999)  
[form]   
An optional argument that specifies the form of the Roman numeral returned This can take any of the following values:

Note that if any of the arguments are input as decimal values, they will be truncated to integers.
The following spreadsheet shows example of the Excel Roman function used to convert the number 9999 to different forms of Roman numerals. The spreadsheet on the left shows the format of the function, and the spreadsheet on the right shows the result.
Formulas:

Results:

Further examples of the Excel Roman function can be viewed on the Microsoft Office website.
If you get an error from the Excel Roman function this is likely to be the following :
#VALUE!   
Occurs if either :
