Roman Numerals

Roman Numerals are terms such as VII, VIII, IX, X, which the Romans invented to denote numbers in ancient times. Roman Numerals are used to represent numbers even today. The use of Roman Numerals is not as common as that of Arabic numerals, primarily because they are not as easy to understand or apply in complex mathematical formulas. Still, they are commonly used in mathematics and in daily life. The table below is helpful when learning about Roman Numerals. 

Table showing Roman Numerals 1 - 100

Using this table, Roman Numerals can be understood easily.

Roman Numerals originated more than 2000 years ago in ancient Rome. The origin can be dated back to 500 BCE. By the end of the Roman Empire, Roman Numerals had become an established method of counting and tallying in various fields, including trade, inscriptions, calendars, and official documents. Even after the fall of the Roman Empire, their numeric system survived and spread across Europe during the Middle Ages. Around the 10th and 12th centuries, Arabic Numerals were introduced, marking a significant shift in the type of Numerals used worldwide. Roman Numerals gradually became outdated and were no longer used as easily as Arabic Numerals. The primary reason for switching from Roman Numerals to Arabic numerals was that the concept of zero was absent in Roman Numerals, which made advanced math and place value concepts impossible. 

Roman numerals are still used widely in:

• Clocks

• Books

• Movies

• Titles

Roman numerals cannot be written or read without learning the rules to use them. Therefore, it is important to know about the rules given below:

Rule 1: Repetition of Letters

This rule states that only certain symbols or letters are allowed to repeat themselves, that too, not more than thrice. Only I, X, C, and M can be written thrice in a row.

 For example, 

Writing ‘I’ three times denotes the number ‘3.’
Likewise, ‘CCC’ indicates 300 and ‘CC’ means 200. Writing ‘C’ once denotes the number ‘100.’ 

Rule 2: Subtraction Principle

We should subtract instead of adding whenever a smaller number comes before a larger number.

For example,

IV = V (5) – I (1) = 4
IX = X (10) – I (1) = 9
XL = L (50) – X (10) = 40

Rule 3: Addition Rule

When the letters are arranged in descending order, from bigger to smaller values, they get added.

For example, 

VI = 5 + 1 = 6
Here V (5) comes before I (1), so V gets added to I to get VI (6)

CL = 100 + 50 = 150
Here C (100) comes before L (50), so C gets added to L to get CL (150)

CXX = 100 + 10 + 10 = 120
Here C (100) comes before XX (20), so C gets added to XX to get CXX (120)

Both Roman and Arabic numerals help us to work with numbers. While ancient Romans used letters like I, X, and C to represent numbers, we use digits like 1, 2, 3, etc. Learning to convert one number system to another will enable us to write and read both systems.

Converting Roman Numerals to Arabic numerals might seem confusing due to the numerous letters involved and rules, but once the process becomes clear, the conversion also becomes easier. The steps for converting Roman Numerals to Arabic numerals are mentioned below.

Step 1: Write the numeric value for each Roman letter in order.
We move left to right while converting Roman Numerals to Arabic numerals.

Step 2: We subtract the value of a numeral if the value of the Numeral is less than its counterpart on the right.

Step 3: Else, if the value of the Numeral on the left is more than the value on the right, we add.

Step 4: The final step is to add the symbol.

Now, let's use an example to understand this method of conversion better. 
Example: Convert the Roman Numeral XCVIII to Arabic Numeral:

First, let's break the Numeral into two parts; this is done to simplify the Roman Numeral.

 
The Numeral can be broken down into XC AND VII. 

Here, XC is 90 because X (10) is smaller than C (100), i.e., the number on the left is smaller than the number on the right, so we subtract.

VIII is eight because V (5) is greater than III (3), so we add V and III. 

Now we know XC is 90 and VIII is 8. Since XC (90) is greater than VIII (8), we should add 90 and 8. So XCVIII is 98.
 

Since we have already learnt about Roman Numeral to Arabic conversions, let us now know the reverse.

Mentioned below is the method of stepwise conversion of Arabic numerals to Roman Numerals:
Step 1: The easiest way to approach a conversion is to break down the number into groups that are easier to solve.

Step 2: After breaking down the Roman number, write the Roman numeral equivalent of each number.
Example: Convert 58 into Roman Numerals:

The number 58 can be broken down into two sets: 50 and 8. This is a good breakdown because there is a predefined value of 50 and 8, which is very common.

The number 50 can be written as L in Roman Numeral terms, and eight can be written as VIII.

Now, to complete the conversion, just add the Roman Numeral, L + VIII = LVIII (58).
 

Roman numerals may have been invented in ancient times, but we still see them in many places today, including clocks and books. Let us take a look at some of the applications of Roman numerals in today’s world:

Clocks and watches: Whenever we want to buy a clock or watch with a vintage look, we are likely to find one with Roman Numerals on it. 

Chapters and events: Roman Numerals are used in numbering book volumes, movie sequels, and parts of a series, among other applications. For example, Shrek 2 will be written as Shrek II, indicating the second part of the movie. 

Years: Years are often represented by Roman Numerals, especially in historical documents and movie credits.

Legal and formal documents: Roman Numerals are used in legal and formal documents to represent the article referenced.

Editions: Editions of various events and objects are represented using Roman Numerals, for example, Super Bowl XVII, Olympics XXIX, etc.

To make children master Roman Numerals, here are a few tips and tricks. These tricks will help you easily understand Roman Numerals.

Learn the Basic Roman Numerals and the numbers that represent them: I(1), V (5), X (10), L (50), C (100), D (500), and M (1000) are the basic Roman Numerals.

We should always memorize the rules before writing Roman Numerals.This will help you write the numbers in Roman Numerals easily.

Break larger numbers large numbers into smaller groups for more straightforward conversion is helpful. For example, break 45 into 40 and 5 - XLV.

Avoid using lowercase to represent Roman Numerals.

Use special characters, such as bars or Roman Numerals, instead of writing long numerical characters