Roman Number System

Roman number system: We have been using the Hindu-Arabic numeral system so far. This is not the only system available. One of the early systems of writing numerals is the system of Roman number system. This system is still used in many places.

Roman Numeral Table

1	I	14	XIV	27	XXVII	150	CL
2	II	15	XV	28	XXVIII	200	CC
3	III	16	XVI	29	XXIX	300	CCC
4	IV	17	XVII	30	$\chi \chi\chi$	400	CD
5	V	18	XVIII	31	$\chi \chi\chi$1	500	D
6	VI	19	XIX	40	XL	600	DC
7	VII	20	XX	50	L	700	DCC
8	VIII	21	XX1	60	LX	800	DCCC
9	IX	22	XXII	70	LXX	900	CM
10	X	23	XXIII	80	L$\chi \chi\chi$	1000	M
11	XI	24	XXIV	90	XC	1600	MDC
12	XII	25	XXV	100	C	1700	MDCC
13	XIII	26	XXVI	101	CI	1900	MCM

Unlike the Hindu-Arabic Numeral System, Roman Numeral System uses 7 basic symbols to represent different numbers. The symbols are as follows :
I = 1 V =5 X= 10
L = 50 C =100 D=500
M= 1000
Rules to form Roman Numerals :
1) If symbol is repeated then its value is added.
2)The symbols I,X,C and M can be repeated maximum 3 times.
3)The symbols V,L and D can never be repeated.
4)If a symbol with smaller value is written on right of greater value then smaller value is added to the greater one.
5)If a symbol with smaller value is written on left of greater value then smaller value is subtracted from the greater one.

Example : 1) Write equivalent Roman numerals of a) 29 b) 395 c)62
Solution : a) 29---> XXIX
b)395 ---> CCCXCV
c) 62 ---> LXII

Example: 2) Write a) XLIV b)DCC in Hindu-Arabic numerals.
Solution : a)XLIV ----> 44
b)DCC ----> 700

Example : 3) Add XXII + CD
Solution :
XXII = 22
CD = 400
XXII + CD = 22 +400
= 422

Example : 4)Add XLIV + LIV
Solution :
XLIV = 44
LIV = 54
∴ XLIV + LIV = 44 + 54
= 98
98 = XCVIII

Example : 5) Subtract DCC - L$\chi \chi\chi$V
Solution :
DCC = 700
L$\chi \chi\chi$V = 85
∴DCC - L$\chi \chi\chi$V = 700 - 84
= 616
616 = DCXVI

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Number System

• Roman number system
• International System of Numeration
• Rounding Numbers

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