In todays modern notation of Roman numerals 1954 is MCMLIV but the ancient Romans would have expressed them quite differently
The Roman numerals are XLV.
20 in Roman numerals is XX.
Arabic ' 12 Roman ; XII Look ant any classical analogue clock, you will see the '12' written in Roman numerals 'XII'.
DCLXVI
MCMLXXXIX
1954 = MCMLIV
The Roman numerals are XLV.
18 in roman numerals looks like XVIII
20 in Roman numerals is XX.
300 would be represented by 'CCC' in roman numerals.
Arabic ' 12 Roman ; XII Look ant any classical analogue clock, you will see the '12' written in Roman numerals 'XII'.
DCLXVI
MCMLXXXIX
XXI
MMDCCCLXXXVI
MCMLII
XL