Originally the characters were notches cut into tally (or counting) sticks in the Etruscan (pre-Roman) era. The Romans adopted them for writing on parchment but substituted the letter in their own...
MLXVI (1066)The year that the Normans invaded England.
They used them to tell time, to measure farm fields, and to count stuff.
the romans used roman numerals like we use numbers but not as many people could write.
Basically, yes. They were the main system of numbers used by the Romans. There were minority numeral systems in Rome, of which is still unknown.