September is the tenth month and would be X. The 18th is represented by XVIII. And the year would be MMXI. So it would normally be shown as X-XVIII-MMXI.
It is: IX-IX-MMXI
IX-XXII-MMXI
IX-XV-MMXI
It is: IX-XXIII-MMXI
XI-XXI-MMXI
The number 2011 converts to MMXI in Roman numerals.
In Roman numerals, the 27th February 2011 is XXVIIth February MMXI
MMXI = 2011
It is: VI-IX-MMXI
October 1, 2011 in Roman numerals is written as X.I.MMXI.
May 6, 2011 in Roman numerals is V VI MMXI
In Roman Numerals that is XXII-III-MMXI.