V xi mdcccci
Another contributor's answer:
Today's conversion of 05 11 1991 into Roman numerals is V-XI-MCMXCI.
The Romans themselves would have most probably chose to write 1991 as MDCCCCLXXXXI.
In today's notation of Roman numerals: XIV-V-MCMXCI
The date 31-05-1987 can be written in Roman numerals as XXXI.V.MCMLXXXVII
V-X-MCMXCI
To write the date 05 08 2005 in Roman numerals, it would be written as V-VIII-MMV.
In Roman Numerals: 05- V 01- I 1984- MCMLXXXIV
In today's notation of Roman numerals: XIV-V-MCMXCI
The date 25-05-2009 written in Roman numerals would be XXV.V.MMIX
The date 31-05-1987 can be written in Roman numerals as XXXI.V.MCMLXXXVII
V-X-MCMXCI
In todays modern era of Roman numerals: V-VII-MCMXCI But the ancient Romans probably wrote out 1991 simply as XMMI (2001-10)
To write the date 05 08 2005 in Roman numerals, it would be written as V-VIII-MMV.
14th May 1987 can also be written as 14-05-1987 and in Roman numerals this would be XIV.V.MCMLXXXVII
In Roman Numerals: 05- V 01- I 1984- MCMLXXXIV
10th May 19** can also be written as 10-05-19** which can be represented by the Roman numerals X.V.MCM (1900)
May 20th 1965 can also be written as 05-20-1965, which can be represented by the Roman numerals V.XX.MCMLXV
May 28th 1975 can also be written as 05-28-1975 and in Roman numerals this would be V.XXVIII.MCMLXXV
The date 12-05-1992 in Roman numerals would be XII.V.MCMXCII