Page 25 - Math 4

Number System Number System

1.14 Roman number system

Roman numerals originated, as the name might suggest, in
ancient Rome. They used only seven basic symbols to write
any number. The seven symbols are I, V, X, L, C, D and M.

Let's know the values of these symbols in Hindu-Arabic
System.

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

There are no special symbols for 2, 3, 4, 6, 7, 8 and 9 in Roman number
system. There is no symbol for zero (0) and there is no way to calculate
fractions in this system.
1.15 Conversion of Roman numerals to Hindu-Arabic numerals

Let's read these rules and examples. Then, learn to convert Roman
numerals into Hindu-Arabic numerals.
Rule 1

We can repeat the symbols I, X, C and M only upto three times. The
repetition of these symbols means addition. The symbols V, L and D are
never be repeated in a number.
Examples

a) II = 1 + 1 = 2 b) XXX = 10 + 10 + 10 = 30

c) LXXV = 50 + 10 + 10 + 5 = 75 d) DCCX = 500 + 100 + 100 + 10 = 710
Rule 2

If a smaller symbol comes before a larger one, the net value is the difference
of values of the symbols.
Examples

a) IV = 5 – 1 = 4 b) IX = 10 – 1 = 9

c) XL = 50 – 10 = 40 d) XC = 100 – 10 = 90

e) CD = 500 – 100 = 400 f) CM = 1000 – 100 = 900
Rule 3

If a smaller symbol comes after a larger one, the net values is the addition
of the values of the symbols.
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vedanta Excel in Mathematics - Book 4
Approved by Curriculum Development Centre, Sanothimi, Bhaktapur v edanta Ex c e l in Mathematics - Book 4