In Roman numerals, the number 1993 is written MCMXCIII. This is the standard form of using Roman numerals that is generally accepted in modern times, although there are alternative forms that have been used throughout the ages.
In Roman numerals, M means 1000, C means 100, X means 10 and I means one. One can add these numerals together to create larger numbers. For example, XIII means 13, represented as 10 + 3. One can also subtract numerals to avoid having to write four of the same symbol consecutively. For example, XC means 90 in the standard form. An alternative way of writing 90 would be LXXXX, where L means 50.