Knowing Our Numbers – Roman Numerals / CBSE Class 6 Mathematics.

CBSE CLASS 6 MATHEMATICS
Knowing Our Numbers – Chapter 1

ROMAN NUMERALS

The Roman numerals I,II,III,IV,V,VI,VII,VIII,IX,X denote 1,2,3,4,5,6,7,8,9 and 10 respectively. This is followed by XI for 11, XII for 12, XIII for 13, XIV for 14, XV for 15, XVI for 16, XVII for 17, XVIII for 18, XIX for 19 and XX for 20.

Some more Roman Numerals are:
I =1, V=5, X= 10, L=50, C=100, D=500 and M= 1000.

The rules for the system are:
a) If a symbol is repeated, its value is added as many times as it occurs.
i.e, II is equal 2, XX is 20 and XXX is 30.

b) A symbol is not repeated more than three times. But the symbols V, L and D are never repeated.

c) If a symbol of smaller value is written to the right of a symbol of greater value, its value gets added to the value of greater symbol.
VI = 5+1 = 6
XII = 10 +2 = 12
LXV = 50+ 10+ 5 = 65

d) If a symbol of smaller value is written to the left of a symbol of greater value, its value is subtracted from the value of the greater symbol.
IV = 5-1 = 4
IX = 10-1 =9
XL = 50 – 10 = 40
XC = 100 -10 = 90

e) The symbols V, L and D are never written to the left of a symbol of greater value, i.e. V, L and D are never subtracted.
The symbol I can be subtracted from V and X only.
The symbol X can be subtracted from L, M and C only.
Following these rules we get,
XL = 40
L= 50
LX = 60
LXX = 70
LXXX = 80
XC = 90
C = 100.

1. Write in Roman numerals:

a) 73
b) 92
c) 69
d) 98

Answers:
a) 73 = 70 + 3 = LXX + III = LXXIII.
b) 92 = 90 +2 = XC + II = XCII
c) 69 = 60 + 9 = LX + IX = LXIX
d) 98 = 90 + 8 = XC + VIII = XCVIII.

Home work:

Write in Roman Numerals:
1. 42
2. 82
3. 89
4. 28
5. 99