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 XXX 400 CD
5 V 18 XVIII 31 XXX1 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 LXXX 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 - LXXXV
Solution :
DCC = 700
LXXXV = 85
∴DCC - LXXXV = 700 - 84
= 616
616 = DCXVI


Number System

Roman number system
International System of Numeration
Rounding Numbers


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