You can't. Romans didn't have a symbol for that. I suppose they'd use this: ∞.
There is none. See John Wallis in the 17th century.
In Roman numerals, 60 is written as "LX".
672 = DCLXXII
[XX]
mcmxcvi
XLIV
C
XIV
XVI
MMCV
It is XXXII.
2003 = MMIII in Roman numerals