ARITHMETIC
Rules to Write Roman numbers
Who invented roman numbers?
Invented in ancient Rome by roman people
Written using seven letters of Latin alphabets
I
Roman numbers do not have symbol for zero
V
X
L
C
D
M
5
10
50
100
500
1000
I
V
M
1
Written using seven letters of Latin alphabets.
Street numbers, roads, buildings
Name of monarchs
Book volumes of books
Hours printed on clocks
Add roman numeral of smaller value to roman numeral of greater value if a smaller value exists on right of roman numeral with greater value
XII
VIII
X + I + I
V + I + I + I
Subtract roman numeral of smaller value from roman numeral of greater value if smaller value exists on left side of roman numeral with greater value
IX
IV
LC
X - I
V - I
L - C
I and X can be used up to three times only.
XII
III
IIII
IIXXXX
XXII
correct
correct
correct
wrong
wrong
The symbols V, L and D are never repeated in a number.
LL
VVLD
VLD
V
L
correct
wrong
wrong
correct
correct
V, L and D are never subtracted.
X + V
XX - V
correct
wrong
How to write 15?
CL
correct
How to write 150?
CC - L
wrong
X can be subtracted from L and C only once.
XL = 50 - 10 = 40
XXC = 100 - 10 - 10 = 80
correct
wrong
I can be subtracted from X and V only once.
IV = 5 - 1 = 4
IIV = 5 - 1 - 1 = 3
correct
wrong
IX = 10 - 1 = 9
correct
C can be subtracted from D and M only once.
CD = 500 - 100 = 400
CCM = 1000 - 100 - 100 = 800
correct
wrong
CM = 1000 - 100 = 900
correct
A bar over a letter means multiply the letter by 1000.
V = 5 x 1000 = 5000
X = 10 x 1000 = 10000
L = 50 x 1000 = 50000
Repeated letters are added up same number of times.
XXX = 10 + 10 + 10 = 30
XX = 10 + 10 = 20
XIII = 10 + 1 + 1 + 1 = 13
Only I, X , C and M can be repeated.
CCC = 100 + 100 + 100 = 300
MM = 1000 + 1000 = 2000
III = 1 + 1 + 1 = 3