# Roman numbers

The Roman numbering system uses uppercase letters, which are assigned values. Roman numerals are mainly used:

• In the chapter numbers a work.
• In the scenes of a theater.
• In the names of popes and emperors.
• In the designation of congresses, Olympics, assembliesâ€¦

## Rules

Roman numbering uses seven uppercase letters, which correspond to the following values:

 Letters Values I 1 V 5 X 10 L 50 Ç 100 D 500 M 1000

Examples: XVI = 16; LXVI = 66.

If to the right of a Roman cipher one is written equal or smaller, its value is added to the value of the previous one.

Examples:
VI = 6
XXI = 21
LXVII = 67

The letter "I" in front of "V" or "X" subtracts one unit; the letter "X" preceding the letter "L" or "C" subtracts ten units and the letter "C" in front of the "D" or "M" subtracts one hundred units.

Examples:
IV = 4
IX = 9
XL = 40
XC = 90
CD = 400
CM = 900

No single letter can be placed more than three times in a row. Formerly you saw the letter "I" or "X" up to four times in a row.
Examples:
XIII = 13
XIV = 14
XXXIII = 33
XXXIV = 34

The letters "V", "L" and "D" cannot be duplicated because other letters ("X", "C", "M") represent their duplicate value.

Examples:
X = 10
C = 100
M = 1,000

If between any two numbers there is a smaller one, the value of this one belongs to the next letter to it.

Examples:
XIX = 19
LIV = 54
CXXIX = 129

The value of Roman numbers when multiplied by one thousand, horizontal bars are placed on top of them.

Examples:

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