Roman numerals and numbers
The Roman numerals used today, Roman numerals  
characters  I  V  X  L  C  D  M  ↁ  ↂ 
value  1  5  10  50  100  500  1.000  5.000  10.000 
As the “Roman numerals” refers to the number of characters created in ancient Roman times and is still in use for numbers and specialpurpose number font,
in the present normal form the Latin letter I (1), V (5) X (10) L (50), C (100) D (500) and M (1000) as numerals for the case of natural numbers are used.
It is an additive number font, with supplementary rule for subtractive case of certain characters, but without place value system and no sign of zero. This is based on a numerical system with the base number of five and ten.
History of Roman numerals
All Roman numerals or Roman numerals were in Central Europe because of their lower aptitude for written arithmetic operations in the period from 12 to 16 Century increasingly in the field of computing and mathematics displaced by the introduced by Arab models written in the decimal system with the arithmetic and the use of zero. Roman numerals remained for other purposes, for the epigraphic or ornamental spelling of numbers, especially for dates, for lists of kings, popes and other carriers of the same name, the band, book, chapter and section count in texts and the numbering of measuring instruments such as the dial of the clock still in use today.
In Roman numerals used characters have a fixed value. There are orders of magnitude than the underlying assets (“One”), the underlying fivefold (“five”). Apart from the subtraction of the value of is independent of the position.
The Roman numerals today?
Today the display with uppercase (capital letters) is common. For page numbering (for example, in the preface, to distinguish from the actual, numbered with Arabic numerals main part of a book), even when alphanumeric classifications are preferably used.
Here are a few good examples of Roman numerals:
How to write 2013 in Roman numerals ?
M (1000) + M (1000) + X (10) + III (3) = MMXIII
How to write 1650 in Roman numerals?
M (1000) + D (500) + C (100) + L (50) = MDCL
Thus, in Roman numerals these simple rules:
Rules

Examples

The Roman numerals are simply added together from left to right, starting always with the greatest number

135 = CXXXV 100 (C) + 10 (X) + 10 (X) + 10 (X) + 5 (V) 
The Roman numerals I, X, C and M may be used a maximum of 3 times side by side, numbers V, L, D only 1x.

3052 = MMMLII 1000 (M) + 1000 (M) + 1000 (M) + 50 (L) + 1 (I) +1 (I) 
When a small figure standing in front of a large,
then this will be subtracted from the larger smaller easy. 
900 = CM 1000 (M) – 100 (C) 
I  1 
II  2 
III  3 
IV  4 
V  5 
VI  6 
VII  7 
VIII  8 
IX  9 
X  10 
XII  12 
XIV  14 
XV  15 
XVII  17 
XIX  19 
XX  20 
XXX  30 
XL  40 
XLIX  49 
L  50 
LX  60 
XC  90 
XCIIX  98 
C  100 
CC  200 
CCC  300 
CD  400 
D  500 
DCC  700 
CM  900 
M  1000 
MCMLVIII  1958 
MM  2000 
MMXIV  2014 
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