Roman Numbers System and Its Application

Roman Numbers:

• We use the Hindu-Arabic system of numerals. Another system of writing numerals is the Roman system.

• The Roman numerals: I, II, III, IV, V, VI, VII, VIII, IX, X denote 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 respectively.

The rules for the system are:

• If a symbol is repeated, its value is added as many times as it occurs:
  i.e., XX is 20 and XXX is 30.

• A symbol is not repeated more than three times. But the symbols V, L and D are never repeated.

• 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 the greater symbol.
  LXV = 50 + 10 + 5 = 65.

• If a symbol of a smaller value is written to the left of a symbol of greater value, its value is subtracted from the value of the greater symbol.
  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.

• Following these rules we get,
  
  

  1	I
  2	II
  3	III
  4	IV
  5	V
  6	VI
  7	VII
  8	VIII
  9	IX
  10	X
  20	XX
  30	XXX
  40	XL
  50	L
  60	LX
  70	LXX
  80	LXXX
  90	XC
  100	C