# 4th Class Mathematics Roman Numerals

Roman Numerals

Category : 4th Class

Roman Numerals

Introduction

The numerals we use is commonly known as Indo-Arabic Numerals. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9__ __ __ __etc. are example of Indo - Arabic numerals. In ancient time Romans developed a system of numerations (numbering) which is known as Roman Numerals. I, II, III, IV, V, VI, VII, VIII, IX, ——— etc. are example of Roman Numerals.

Roman numerals are formed by using the following symbols:

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

Rules to write Roman Numerals

Rule 1: If a symbol is repeated in a Roman numeral, the value of the Numeral is obtained by adding the value of the symbols.

• Example

Find the Hindu-Arabic numeral for II and XX.

Solution:

II = 1 + 1 = 2,

XX = 10 + 10 = 20

• Example

Find the Hindu-Arabic numeral for XXX.

Solution:

$XXX=10+10+10=30$

Rule 2: In a Roman numeral, if a symbol at the left have greater value than the symbol at the right, then add the values of these two symbols.

• Example

Find the value of the roman numerals CL and LX.

Solution:

CL = 100 + 50 = 150

LX = 50 + 10 = 60

• Example

Find the value of the Roman numeral MC.

Solution:

$MC=1000+100=1100$

Rule 3: In a Roman numeral, if a symbol at the right have greater value than the symbol at the left, difference of their value is the resulting value.

• Example

Find the value of roman numerals CM and XC.

Solution:

CM = 1000 = 100 = 900

XC = 100 - 10 = 90

• Example

Find the value of Roman numeral CD.

Solution:

$CD=500-100=400$

Rule 4: The symbols I, X, C and M can be repeated in a roman numeral whereas V, L and D cannot be repeated.

• Example

Write the correct numeral for Roman numeral DCC. Solution:

$DCC=500+100+100=700$

• Example

Why the Roman numeral MLL is not valid?

Solution:

In the numeral the symbol L has been repeated twice. Therefore, MLL is not a valid Roman numeral.

Rule 5: When a Roman symbol of smaller value is placed between two symbols of greater value, its value is subtracted from the value of the symbol to its right.

• Example

Find the value of the Roman numeral LIX.

Solution:

$LIX=50+(10-1)=59$

• Example

Find the value of the Roman numeral XIV.

Solution:

$XIV=10+(5-1)=14$

Note: No symbols can be repeated more than three times

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