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Two versions in Python code can be viewed here and here.

Convert Decimal Integer to Roman Integer

Enter a decimal integer between 1 and 3999 inclusive.

The Roman integer is MMXVI.

Convert Roman Integer to Decimal Integer

Enter a Roman integer between 1 and 3999 inclusive.

The decimal integer is 2016.

Add Two Roman Integers

Enter a Roman integer between 1 and 3999 inclusive.

Enter a second Roman integer between 1 and 3999 inclusive.

The Roman sum is (V)MMCMXCVIII.

The addition is performed by a method the Romans may have used.
The notation (V) is used to indicate 5000.

Compare Two Roman Integers

Enter a Roman integer between 1 and 3999 inclusive.

Enter a second Roman integer between 1 and 3999 inclusive.

The Roman integers are equal.

The comparison is performed by a method the Romans may have used.

Subtract one Roman Integer from another Roman Integer.

Enter a Roman integer between 1 and 3999 inclusive.

Enter a second Roman integer between 1 and 3999 inclusive.

The Roman difference is MMCCXXII.

The subtraction is performed by a method the Romans may have used.

Multiply Two Roman Integers

Enter a Roman integer between 1 and 3999 inclusive.

Enter a second Roman integer between 1 and 3999 inclusive.

The Roman product is (V)MMDLII.

The multiplication is performed by a method the Romans may have used.

The notation (V) is used to indicate 5000, (L) to indicate 50000, etc.
In general, ( ) indicates one thousand times the basic numeral,
(( )) indicates one million times the basic numeral.

Roman Multiplication Table

| I V X L C D M |
___|_____________________________________________________|___
| |
I | I V X L C D M |
| |
| |
V | V XXV L CCL D MMD (V) |
| |
| |
X | X L C D M (V) (X) |
| |
| |
L | L CCL D MMD (V) (XXV) (L) |
| |
| |
C | C D M (V) (X) (L) (C) |
| |
| |
D | D MMD (V) (XXV) (L) (CCL) (D) |
| |
| |
M | M (V) (X) (L) (C) (D) (M) |
___|_____________________________________________________|___
| |

Divide one Roman Integer by another Roman Integer.

Enter a Roman integer between 1 and 3999 inclusive.

Enter a second Roman integer between 1 and 3999 inclusive.

The Roman quotient is CCLXIV and the remainder is VIII.

A zero quotient is indicated by the symbol N (nulla).

The divison is performed by a method the Romans may have used.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the
GNU General Public License
along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin
St, Fifth Floor, Boston, MA 02110-1301 USA