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Lesson 2, Topic 1
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# Roman Numerals

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Roman numerals are number systems that originated in ancient Rome and remained the usual way of writing numbers throughout Europe. Numbers in this system are represented by combinations of letters from Latin alphabets.

Roman Numerals used capital letters of the alphabet for numerals as shown below;

Roman numerals were first used about 2,500 years ago. They are still used presently, on clock faces, chapter numbers in books, etec.

Basic Combinations:

### Forming Numbers (Rules):

Rule 1: When a symbol appears “after a larger” (or equal) symbol it is added.

Rule 2: When the symbol appears “before a larger” symbol it is subtracted.

Roman big numbers:

Example 1

Change these Roman numerals to ordinary numbers:

1. CXLVI

2. CCCLXXXVII

3. DCCCIX

Solution

1. Working from the left-hand side (LHS)

CXLVI Means

C   +  XL +  VI

C = 100

XL = 40

VI = 6

∴ 100 +  40 +   6  = 146

∴ CXLVI  = 146

2. CCCLXXXVII

CCC = 300

L = 50

XXX = 30

VI = 7

∴ 300 + 50 + 30 + 7

∴ CCCLXXXVII = 387

3. DCCCIX

D = 500

CCC = 300

IX =     9

∴ 500 + 300 + 9

∴ DCCCIX = 809

Example 2

Convert the following numerals to Roman Figures

a. 39

b. 118

c. 1584

Solution

a. 39 =  30 + 9 = 39

30 = XXX, 9 = IX

XXX +  IX = XXXIX

39 = XXXIX

b. 118 = 100 + 10 + 8

C   +  X  +  VIII

118 = CXVIII

c. 1584 = 1000 + 500 + 80   +   4

1000 = M, 500 = D, 80 = LXXX, 4 = IV

= M   +    D  +   LXXX  + IV

1584  =  MDLXXXIV error: