Today we write out 99 in Roman numerals as XCIX because XC = 90 and IX = 9. Therefore it logically follows that XC+IX = XCIX as in the case of Hindu-Arabic numerals. But the R … oman numeral system does not contain a zero figure for positional place value purposes.   The seven symbols used for Roman numerals are:-   M=1000, D=500, C=100, L=50, X=10, V=5 and I=1    Roman numerals are the numbering system that the Romans used.