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Roman Numeral Calculator

To use the Roman number calculator, Select the arithmetic operation, enter the two values into their designated boxes, and Click Calculate.

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Roman numeral Calculator 

Roman numeral calculator is an arithmetic tool that performs basic mathematical operations on numbers; the numbers are Roman and not decimal

What are Roman Numerals?

Roman numerals are a number system originating from ancient Rome. They use combinations of letters from the Latin alphabet to represent values. Here are the basic symbols and the values they represent:

  • I: 1
  • V: 5
  • X: 10
  • L: 50
  • C: 100
  • D: 500
  • M: 1000

Rules for constructing numbers with Roman numerals:

  • Repeating a numeral up to three times represents the addition of the number. For instance, III = 3.
  • Only one smaller number may be placed to the left of a larger number to indicate subtraction. For instance, IV = 4 (5 - 1) and IX = 9 (10 - 1).
  • If a numeral is placed after a larger or equal numeral, it is added. For instance, VI = 6 (5 + 1) and XX = 20 (10 + 10).

In the subtraction cases, the smaller numeral must be I, X, or C. The larger numeral must be a numeral with a value no more than 10 times larger than the smaller numeral. I can be subtracted only from V and X. X can be subtracted only from L and C. C can be subtracted only from D and M.

So using these rules, here are some examples:

  • II = 2
  • VII = 7
  • XII = 12
  • XXVII = 27
  • XC = 90
  • CIII = 103
  • MCMXCVI = 1996
  • MMXXIII = 2023

This system does not have a concept of zero and does not use the place-value system, which makes it quite different from the decimal numeral system, which is widely used today.

How to perform arithmetic operations on Roman numerals?

Performing operations on Roman numerals is very tricky and time-consuming. This is why they are first converted to decimal numbers and then the result is converted to Roman numerals.

  1. Addition

Let's add XII (12) and XVI (16).

Convert to decimal numerals: 12 + 16 = 28

Convert back to Roman numerals: 28 = XXVIII

So, XII + XVI = XXVIII.

  1. Subtraction

Subtract XVI (16) from XX (20).

Convert to decimal numerals: 20 - 16 = 4

Convert back to Roman numerals: 4 = IV

So, XX - XVI = IV.

  1. Multiplication and Division

For example, to multiply III (3) by IV (4):

Convert to decimal numerals: 3 * 4 = 12

Convert back to Roman numerals: 12 = XII

So, III * IV = XII.

It's important to note that while it's possible to do these operations using Roman numerals, it's not how they were historically used. The Romans did not use these methods; instead, they would have used other techniques, like the use of an abacus, to perform arithmetic operations.

Table for Roman numerals:

Roman numerals 

Decimal number

I

1

II

2

III

3

IV

4

V

5

VI

6

VII

7

VII

8

IX

9

X

10

XX

20

XXX

30

XL

40

L

50

LX

60

LXX

70

LXXX

80

XC

90

C

100

CD

400

D

500

CM

900

M

1000

X
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