Roman Numeration Scheme
Department of Mathematics and Computer Studies
York College (CUNY)
Jamaica, New York 11451
The Roman Numeration Scheme used letters to represent numbers.
M = 1000
D = 500
C = 100
L = 50
X = 10
I = 1
The meaning of the letters sometimes depends on the position of the letters relative to each other. Thus, IX and XI represent 9 and 11 respectively.
If a number which represents a smaller number appears to the left on one which represents a larger number, this indicated the smaller number is to be subtracted from the larger one. Thus XC = 90, and XLIV = 44.
MCDXXXI represents 1431.
Other enhancements to the system were used in more recent times to make the system easier to use. In fact, the "subtraction" mechanism (e.g. IV for 4) seems to not have been used that much in ancient times.