In todays modern notation of Roman numerals 1954 is MCMLIV but the ancient Romans would have expressed them quite differently
12 = XII in Roman numerals
1954 = MCMLIV
The Roman numerals are XLV.
18 in roman numerals looks like XVIII
300 would be represented by 'CCC' in roman numerals.
MDCCCXCV
MMDCCCLXXXVI
MCMLXXXV
MCMLXV
XL
MCMLII
mmxiii