# Roman Numerals

Let us gain knowledge of Roman numerals.

In ancient times, many civilizations used different number systems. Mayans, Egyptians, Indians, Romans, etc had their own number system.

The numbers from 0-9 were first invented in India. Later, the Arabs were greatly influenced by this number system and started using it. The Arabs also introduced this number system in Europe. Now, this number system is used worldwide and is called the Hindu-Arabic number system.

Just like this, the Romans used their own number system for counting. Today, we use these roman numerals in clocks and watches. Ancient Romans used “7” letters to write numbers. These letters were I, V, X, L, C, D, and M. The combination of these numbers makes the roman numerals. Where

 I V X L C D M 1 5 10 50 100 500 1000

The roman numerals from 1-100 are – It is to be noted, there is no representation for “0(zero)” in the roman numerals.

#### Rules for Roman Number System

• Rules for repetition
• If a symbol is repeated, its value is added as many times as it occurs. For e.g.
X = 10
Then, XX= 10+10 = 20
And    XXX = 10+10+10 =30
Let us take another example,
M = 1000
and MM = 1000+1000 =2000
also, MMM =1000+1000+1000 = 3000

• A symbol is never repeated more than three times.
• for example,
• I = 1
• II = 2
• III=3
• But IIII ≠ 4 Thus it is written as IV = 4.
• The symbol V, L and D are never repeated.
For example,
V = 5
but VV ≠ 10
and X = 10

• When the symbol of smaller value is written to the right of greater symbol value, its value gets added to the value of greater symbol. For e.g.
VII = 5 + 2
and XI = 10 + 1 = 11
LXVI = 50 + 10 + 6 = 66

#### For subtraction

If a symbol of a smaller value is written to the left of a symbol of greater value, its value is subtracted from the value of the greater symbol.
e.g
IX = 10 – 1 = 9
XL = 50 -10 = 40

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.

Also, The symbol I can be subtracted from V and X only. And X can be subtracted from L, M and C only.

Let us solve some questions.

Question 1 : What is the roman numerals of
(i) 121
Solution- 121 = 100 + 20+ 1
or                     =  C + XX + I
= CXXI
Therefore, roman numeral of 121 is CXXI.

(ii) 799
Solution –
799 = 700 + 90 + 9
= (500 + 100 + 100) + 90 + 9
= ( D + C+ C) + XC + IX
= DCCXCIX
Therefore, the roman numeral of 799 is DCCXCIX.
(iii) 303
Solution –
303 = 300 + 3
= (100 + 100 + 100 ) + 3
= ( C + C + C ) + III
= CCCIII
Therefore, the roman numeral of 303 is CCCIII.

Question 2: What is the Hindu-Arabic numeral of
(i) CMIV
Solution- CMIV
We know,       C = 100 , M = 1000 and IV = 4
CMIV = (1000 -100 )+ 4
= 900 + 4
= 904
Therefore, the Hindu-Arabic numeral of CMIV is 904.
(ii) DIX
Solution – DIX
D = 500 and IX = 9
Thus, DIX = 500 + 9
= 509
Therefore, the Hindu – Arabic numeral of DIX is 509.
(iii) CCXLV