Page 29 - Revised Maths Wisdom Class - 3

4-Digit Numbers 27

Roman Numbers

We have used the numbers 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 to write any number previously. This
is known as Hindu-Arabic number system.

In Roman number system, we use 7 lett ers of the alphabet to write all the Hindu-Arabic
numbers.

Roman Numbers I V X L C D M
Value in Hindu-Arabic Numbers 1 5 10 50 100 500 1000

We can use combination of these seven lett ers to make diff erent numbers but certain
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rules are to be followed:

Rule 1: I, X, C and M can be repeated up to three times. The number so formed is their

sum. For example,
III = 1 + 1 + 1 = 3, XX = 10 + 10 = 20

Rule 2: V, L and D are never subtracted.

Rule 3: When we write a smaller Roman number aft er a greater Roman number, their
values are added. For example,

VI = 5 + 1 = 6 XI = 10 + 1 = 11

XXII = 10 + 10 + 1 + 1 = 22 VII = 5 + 1 + 1 = 7
XII = 10 + 1 + 1 = 12 XV = 10 + 5 = 15

XXXVII = 10 + 10 + 10 + 7 = 37 XIII = 10 + 1 + 1 + 1 = 13

VIII = 5 + 1 + 1 + 1 = 8
Rule 4: When we write a smaller Roman number before a greater Roman number, their
values are subtracted. For example,

IV = 5 – 1 = 4 IX = 10 – 1 = 9

Rule 5: A smaller number between two greater numbers gets subtracted from the
number on its right. For example,

XIV = 10 + (5 – 1) = 14 XIX = 10 + (10 – 1) = 19

XXIX = 10 + 10 + (10 – 1) = 29
XXIX = 10 + 10 + (10 – 1) = 29

emember!
emember!
emember!
 4 is never writt en as IIII.
 There is no symbol for zero in Roman number system.
 There is no concept of place value in Roman number system.