Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages.Numbers in this system are represented by combinations of letters from the Latin alphabet.Modern usage employs seven symbols, each with a fixed integer value. This online Roman Numerals to Numbers Converter helps you to convert one Roman Numeral into a number (base 10). Put Roman Numeral into the first textbox, the number result will show in the second textbox.

Roman Numerals can be tricky to understand – that’s why we’ve got a great roman numeral converter – but if you want to know how to convert the numbers yourself. Here is a guide..

The Basics.. There are 7 numbers to learn:

Learn these 7 number units - Every Roman Numeral is made from a combination of these 7 numbers:

• I = 1
• V = 5
• X = 10
• L = 50
• C = 100
• D = 500
• M = 1000

ADD the numbers up from Left to Right..

III = 1 + 1 + 1 = 3
VII = 5 (V) + 1 + 1 = 7

Simple so far!

A little bit trickier..

Always use as BIG number unit as possible to make the number you want:
Example:

• 6 would be V (for 5) and I (for 1). VI NOT IIIIII (1,1,1,1,1,1)
• 15 would be X (for 10) and (V for 5). XV NOT VVV (5,5,5)
• 156 would be C (for 100), L (for 50), V (for 5) and I (for 1). CLVI NOT LLLIIIIII (50,50,50,1,1,1,1,1,1)

So remember – use as BIG number as possible – not smaller ones! It helped save time writing!

The trickiest part!

This is where Roman numerals can get difficult – To make it even quicker to write numbers, the Romans decided to use 6 extra numbers, they are:

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

• So instead of writing IIII for 4 – Romans could now write IV.
• Instead of LXXXX for 90 – They could now write XC. A great time saver!

What these new numbers did was tell you to SUBTRACT the small number, if it is on the LEFT side of a big number.

• VI = 6 (With the I on the RIGHT of the V - Add)
• IV = 4 (With the I on the LEFT of the V - Subtract)

It's important to know though – that ONLY these 6 new combinations can be used together – so IX is a pair – meaning 9 – but you cannot have IL for 49. (It’s best just to learn the new 6 numbers!)

So how would you write 99?
To write 99 – you use XC for 90, then IX for the 9 – The answer: XCIX
Without the 6 new numbers - only the original 7, it would have been: LXXXXVIIII
(And just using Is would be: IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIII)

Roman numerals are a system of numerical notations used by the Romans. They are an additive (and subtractive) system in which letters are used to denote certain 'base' numbers, and arbitrary numbers are then denoted using combinations of symbols. Unfortunately, little is known about the origin of the Roman numeral system (Cajori 1993, p. 30).

The following table gives the Latin letters used in Roman numerals and the corresponding numerical values they represent.

character	numerical value
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

For example, the number 1732 would be denoted MDCCXXXII in Roman numerals. However, Roman numerals are not a purely additive number system. In particular, instead of using four symbols to represent a 4, 40, 9, 90, etc. (i.e., IIII, XXXX, VIIII, LXXXX, etc.), such numbers are instead denoted by preceding the symbol for 5, 50, 10, 100, etc., with a symbol indicating subtraction. For example, 4 is denoted IV, 9 as IX, 40 as XL, etc. However, this rule is generally not followed on the faces of clocks, where IIII is usually encountered instead of IV. Furthermore, the practice of placing smaller digits before large ones to indicate subtraction of value was hardly ever used by Romans and came into popularity in Europe after the invention of the printing press (Wells 1986, p. 60; Cajori 1993, p. 31).

The following table gives the (Europeanized) Roman numerals for the first few positive integers.

#	RN	#	RN	#	RN
1	I	11	XI	21	XXI
2	II	12	XII	22	XXII
3	III	13	XIII	23	XXIII
4	IV	14	XIV	24	XXIV
5	V	15	XV	25	XXV
6	VI	16	XVI	26	XXVI
7	VII	17	XVII	27	XXVII
8	VIII	18	XVIII	28	XXVIII
9	IX	19	XIX	29	XXIX
10	X	20	XX	30	XXX

For large numbers, the Romans placed a partial frame around numbers (open at the bottom), which indicated that the framed number was to be multiplied by , as illustrated above (Menninger 1992, p. 44; Cajori 1993, p. 32). In more recent practice, the strokes were sometimes written only on the sides, e.g., (Cajori 19993, p. 32). It should also be noted that the Romans themselves never wrote M for 1000, but instead wrote (I) for , (I)(I) for , etc., and also occasionally wrote IM, IIM, etc. (Menninger 1992, p. 281; Cajori 1993, p. 32). However, in the Middle Ages, the use of M became quite common. The Romans sometimes used multiple parentheses to denote nested multiplications by 10, so (I) for , ((I)) for , (((I))) for , etc. (Cajori 1993, p. 33).

The Romans also occasionally used a vinculum (called a titulus in the Middle Ages) over a Roman numeral to indicate multiplication by 1000, so , , etc. (Menninger 1992, p. 281; Cajori 1993, p. 32).

Roman numerals are encountered in the release year for movies and occasionally on the numerals on the faces of watches and clocks, but in few other modern instances. They do have the advantage that addition can be done 'symbolically' (and without worrying about the 'place' of a given digit) by simply combining all the symbols together, grouping, writing groups of five Is as V, groups of two Vs as X, etc.

The number of characters in the Roman numerals for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, .. (i.e., I, II, III, IV, V, VI, VII, VIII, IX, X, ..) are 1, 2, 3, 2, 1, 2, 3, 4, 2, 1, 2, 3, 4, .. (OEIS A006968). This leads to a scale-invariant fractal-like stairstep pattern which rises in steps then falls abruptly.

SEE ALSO:Arabic Numeral, GreekNumeralsREFERENCES:

Cajori, F. A History of Mathematical Notations, 2 vols. Bound as One, Vol. 1: Notations in Elementary Mathematics. New York: Dover, pp. 30-37, 1993.

Menninger, K. Number Words and Number Symbols: A Cultural History of Numbers. New York: Dover, pp. 44-45 and 281, 1992.

Neugebauer, O. TheExact Sciences in Antiquity, 2nd ed. New York: Dover, pp. 4-5, 1969.

Sloane, N. J. A. Sequence A006968/M0417in 'The On-Line Encyclopedia of Integer Sequences.'

Villegas, R. 'Antique Notations.' https://library.wolfram.com/infocenter/Demos/4952/.

Wells, D. The Penguin Dictionary of Curious and Interesting Numbers. Middlesex, England: Penguin Books, pp. 60 and 79, 1986.

Wolfram, S. 'Mathematical Notation: Past and Future.' Transcript of a keynote address presented at MathML and Math on the Web: MathML International Conference 2000. October 20, 2000. https://www.stephenwolfram.com/publications/talks/mathml/.

Referenced on Wolfram Alpha: Roman NumeralsCITE THIS AS:

Weisstein, Eric W. 'Roman Numerals.' FromMathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/RomanNumerals.html