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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:

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 can not 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:

\[LIX=50+\left( 10-1 \right)=59\]

•           Example

Find the value of the roman numeral XIV.

Solution:

\[XIV=10+\left( 5-1 \right)=14\]

Note: No symbols can be repeated more than three times