1. By.. Miss Prangtip Kaewsuphot
Roman Numeral
By..
Miss Prangtip Kaewsuphot

2. A number system is a set of characters and mathematical rules
rules that are used to represent number. Examples include
the Arabic, Babylonian, Chinese, Egyptian, Greek,
Mayan and Roman number systems.
Roman Numerals represented the standard numbering
system and method of arithmetic in ancient Rome and Europe.
It was developed 2000 years ago. The system used seven letters
of the alphabet to write any number. These are as follows.
I = X = C = M =
V = L = D =

3. There is no zero in the Roman system
There is no zero in the Roman system. An important difference between the decimal system and the Roman system is that the Roman system does not use place value. Study the following rules to read and write numerals in the Roman system. Rule 1 : Numerals I, X, C and M can be repeated to represent a number. Repetition of these numerals means addition. e.g. II = 2, XXX = 30, CCC = 300, MM = The symbol I, X and C can not be repeated than 3 times in a numeral, e.g. 4 is written as IV, not IIII. Symbols, V, L, D, are not repeated.

4. Rule 2 : A smaller numerals written to the right of a numeral of greater
value is always added to greater numeral.
e.g. VII = = XI = = 11 LX = = 60
MC = 1100
Rule 3 : A smaller numeral written to the left of a numeral of greater
value is always added to the greater numeral.
e.g. IV = 5 – 1 = 4 XC = 100 – 10 = 90
CD = 500 – 100 = CM = – 100 = 900
Rule 4 : When a smaller numeral is placed between two numerals of
greater value, it is always subtracted from the greater numeral immediately
Following it.
e.g. XXX = (10 – 1) = 29, DIX = (10 – 1) = 509

5. * The symbol I can be subtracted from V and X.
* The symbol X can be subtracted from L and C.
* The symbol C can be subtracted from D and M.
* Symbols V, L, D are never subtracted.
Write in Roman numerals.
3429 =
= MMM + CC + XL + IX
= MMMCCXLIX
Write MDCLXVII in denary system.
MDCLXVII = M + DC + LX + VII =
= 1667

6. EXERCISE 1. Write the following numbers in Roman numerals.
(ii) (iii) (iv) (v) 312
(vii) (viii) (ix) (x) 1347
(xii) 2350
2. Write the following numbers in decimal notation.
XXVII (ii) XXXIX (iii) DXC
LIX (v) DCCLXXVI (vi) CMLXIX
CCXVII (viii) CDIV (ix) CMLXXI
(x) MXXXIV (xi) MCXI (xii) MCCXLVII

7. Points to remember
The seven letters of the alphabet – I, X, C, M, V, L, D are used as basic symbols to write any number in Roman system of numeration.
The Roman System does not have zero.
3. The Roman System does not use place value.

8. Story Time … The history of Roman numerals and Roman mathematics
isn’t well documented. The development of the numeric symbols
may have been closely related, originally, to the shape of the hand:
I for a single finger, V for the whole hand outstretched, X for
both hands in the same manner.