Letters are not numbers. Not all letters in the alphabet represent Roman numerals though some letters do.
The Romans did but these letters or numerals represented numbers.
with the keyboard letters
A) Arabic numerals are in numbers whereas Roman numerals are in letters.B) Even if Roman numerals are in letters the symbols are easier to understand, despite the fact that Australians and Americans and most probably you write numbers using the system of Arabic numerals.C) The system of Roman numerals was invented before the system of Arabic numerals, but people use the system of Arabic numerals to write more frequently.
Roman numerals are numbers.
You have written them in numerals
As any other roman numerals...with letters.
3210 = MMMCCX in Roman numerals which are expressed in letters
Using Roman Numerals: VI/IX/MMXI uses a total of 4 letters.
There is no O and E in Roman Numerals.
The roman numerals don't have a way to write 0, negative numbers, or fractions.