There is no symbol for zero in the Roman numeral system. The Romans did not use their numerals for arithmetic, so they avoided the need to keep a column empty with a zero symbol. Instead, they used the Latin word "nulla," which means "none," to represent zero. If they needed to express the concept of "nothing," they would use the word "nullus". The Roman numeral system was developed for trading and bartering, and they did not need a numeral to represent zero.