Converting Roman Numerals To Decimal

In this post we will write a java program to convert Roman Number to Decimal. Before start our program, lets see what are the roman numbers and its decimal values below.

Roman Numbers and its decimal values:

Roman Symbol	Decimal value
I	1
IV	4
V	5
IX	9
X	10
XL	40
L	50
XC	90
C	100
CD	400
D	500
CM	900
M	1000

Decimal Forming Rules:

1. When a symbol appears after a larger or equal symbol, then it is added

• VI = V + I = 5 + 1 = 6
• XXI = X + X + I = 10 + 10 + 1 = 21

2. But if the symbol appears before a larger symbol, the it is subtracted

• IV = V - I = 5 - 1 = 4
• IX = X - I = 10 - 1 = 9

Java Program:


Output:

Enter roman value : VI

It's Decimal value : 6

Enter roman value : XC

It's Decimal value : 90

Enter roman value : MCMLXXXIV

It's Decimal value : 1984