1954 = MCMLIV
In todays modern notation of Roman numerals 1954 is MCMLIV but the ancient Romans would have expressed them quite differently
18 in roman numerals looks like XVIII
The Roman numerals are XLV.
300 would be represented by 'CCC' in roman numerals.
MCMLXXXIX
DCLXVI
VII
MCMLII
XXI
XL
MCMLXV
MMI