The Roman numeral M corresponds to the Arabic number 1000.
M = 1000
Symbols are written and read from left to right, from highest to lowest.
If number M is within to text or sentence it should be read in its equivalent in Arabic numbers, in this case 1000.
CMXCIX is number 999
MI is number 1001
Calculate the conversion of any number and its equivalent in Roman numerals with our Roman numerals converter.