Roman Numerals

 

Roman numerals are a system of numerical notations used by the Romans.

They are an additive (and subtractive) system in which letters are used to denote certain "base" numbers.

The rules for the system are :

  • If a symbol is repeated, its value is added as many times as it occurs:

For example:  II equals to 2;  XX  equals to 20 and  XXX equals to 30.

 
  • If a symbol of smaller value is written to the right of a symbol of greater value, its value gets added to the value of greater symbol.
  • VII = 5 + 2 = 7, XII = 10 + 2 = 12 and  LXV = 50 + 10 + 5 = 65
  • If a symbol of smaller value is written to the left of a symbol of greater value, its value is subtracted from the value of the greater symbol.    

For Example:

V = 5 – 1 = 4, IX = 10 – 1 = 9  XL= 50 – 10 = 40, XC = 100 – 10 = 90

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

Demonstration:

Write in Roman Numerals (a) 69 (b) 98.

Solution: (a) 69 = 60 + 9 (b) 98 = 90 + 8

= (50 + 10) + 9 = (100 – 10) + 8

= LX + IX = XC + VIII

= LX IX = XCVIII