Conversion of Roman Numbers to Numbers & Vice Versa – Rules, Steps, Examples

Lets us learn how to convert roman numerals. So the first thing we need to know is the letters and the numbers that relate to them. By going through this article, you will become familiar with the conversions of roman numerals to Hindu Arabic numbers and vice versa. In addition, we have even jotted down the rules for converting numbers to Roman Numerals and roman numerals to numbers along with solved examples.

Below is the table of some of the frequently used Roman Numerals and their equivalent Hindu Arabic numbers.

Commonly Used Roman Numerals and their Equivalent Numbers

Symbols I V X L C D M
Numbers 1 5 10 50 100 500 1000

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How to Convert Roman Numerals to Hindu-Arabic Numbers?

We have to follow certain rules while converting Hindu–Arabic numerals into roman numbers as mentioned below

  • Each symbol can only be repeated three times.
  • Always remember if a smaller number is placed before a larger number, the number has the effect of addition. Which means the smaller number must be added to the larger number.
  • And if a smaller number is placed after a larger number then we have to perform subtraction, which means we have to subtract the smaller numbers from the larger numbers.

Rules for Converting Numbers to Roman Numerals

We can covert Hindu–Arabic numerals into roman numbers by following a simple step-by-step process as mentioned below

Step 1: Always expand the given number into thousands, hundreds, tens, and ones. This means we have to divide the given number according to its units.
Step 2: Now after expanding the number we have written the symbols using our standard roman numerals and rules

Now let’s see few examples of how to convert the Hindu – Arabic numbers to roman numbers.

Conversion of Numbers to Roman Numerals Examples

Example 1:
Let’s convert 1526 into Roman numerals

Solution:

We have to expand our number to convert so,
1526 can be expanded as 1000 + 500 + 20 + 6
Now we know 1000 is M, 500 is D and VI is 6 from the above table.
= M D 20 + VI
But we don’t know have roman numerals for 20. So we have to expand 20 as
20 = 10 + 10
= XX
So now our roman numeral for 1526 will be MDXXVI

Example 2:
Let’s convert 1879 into Roman numerals

Solution:

We have to expand our number to convert so,
1879 can be expanded as 1000 + 800 + 70 + 9
Now we know 1000 is M, and IX is 9 from the above table.
= M 800 + 70 + IX
But we don’t know have roman numerals for 800 and 70. So we have to expand them as.
800 = 500 + 100 + 100 + 100 and 70 = 50 +10 +10
= D C C C and = L X X
So now our roman numeral for 1879 will be MDCCCLXXIX

Example 3:
Let’s convert 911 into Roman numerals

Solution:

We have to expand our number to convert so,
911 can be expanded as 900 + 10 + 1
Now we know 10 is X, and I is 1 from the above table.
= 900 + X + I
But we don’t know have roman numerals for 900. So we have to expand them as.
900 = 1000 – 100
= CD
So now our roman numeral for 991 will be CDXI

Rules for Conversion of Roman Numerals to Numbers

We have to follow certain rules while converting roman numbers into Hindu – Arabic numerals as mentioned below

  • Find the largest Roman Numeral by using the decimal value.
  • Now if the largest numeral appears first then we have to count how many times it is repeated. Remember a number can’t be repeated more than three times.
  • Now if the number is repeated, multiply its value by the number of times it is repeated and then add the value of roman to the value of the decimal number.
  • If incase largest numeral appears second then subtract the value of the number before its value.
    We have to repeat the above steps till we get our number.

How to Convert Roman Numerals to Hindu Arabic Numbers?

We can covert roman numbers into Hindi – Arabic Numerals by following a simple step-by-step process as mentioned below

  • When a roman number is given we have initially split the given number into digit, double digit, triple digit, quadruple-digit symbols
  • Now after splitting our given roman number we have to follow the rules mentioned above to obtain result.

Roman Numerals to Hindu Arabic Numbers Examples

Now let’s see few examples of how to convert the roman numbers into Hindu – Arabic numerals.

Example 1:
Convert MDCCXI into Hindu- Arabic numeral?

Solution:

We have to split it into single digit, double digit, triple digit, quadruple digit symbols so MDCCXI can be split as M + D + C +C + X + I
Now we know M is 1000, D is 500, C is 100, X is 10 and I equals to 1 from the above table.
= 1000 + 500 + 100 + 100 + 10 + 1
= 1711
So now our Hindu- Arabic numeral for MDCCXI is 1711

Example 2:
Convert MCMLX into Hindu- Arabic Numeral?

Solution:

We have to split it into a single digit, double-digit, triple-digit, quadruple-digit symbols so MDCCXI can be split as M + CM + L + X
Now we know M is 1000, D is 500, C is 100, X is 10 and I equals 1 from the above table.
= 1000 + 900 + 50 + 10 (Here CM is 900)
= 1960
So now our Hindu- Arabic numeral for MCMLX is 1960

Example 3:
Convert DCCXLIII into Hindu- Arabic Numeral?

Solution:

We have to split it into single-digit, double-digit, triple-digit, quadruple digit symbols so DCCXLIII can be split as D + C + C + XL + III
Now we know M is 1000, D is 500, C is 100, X is 10 and I equals to 1 from the above table.
= 500 + 100 + 100 + 40 + 3 (Here XL is 40)
= 743
So now our Hindu- Arabic numeral for DCCXLIII is 743

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