Roman Numerals: When and How to Use Them? Learn Now!

You've probably already used Roman numerals, perhaps out of habit or simply out of your own free will.

But do you really know how Roman numerals work? Let's find out now!

What are Roman numerals?

Roman numerals are a numbering system created during the Roman Empire and which was widely used throughout Europe, long before being replaced by the Arabic system used today.

The Roman numeral system was not the first based on letters, the Greeks and Babylonians already used it in ancient civilizations, and the system adopted by the Romans was similar to these.

But still talking about this numbering, they are composed of letters from the Latin alphabet, used to represent what we know today as normal numbers, 1, 2, 3, 4 and so on.

According to history, the numbers derive from the Etruscans, a civilization before the Romans that inhabited the Italian Peninsula, their numbers were carved, and what the Romans did was just adapt.

This system began during the Roman Empire and was used until the 15th century (XV), since the use of the decimal system was introduced from the 16th century (XVI).

What are the main ones?

Since we know that Roman numerals are represented by letters, we can also better understand which are the main ones that we will use to learn more.

Let's see what they are:

• I – 1;
• V – 5;
• X – 10;
• L – 50;
• C – 100;
• D – 500;
• M – 1000.

Roman numeral rules

With these seven numbers, you will be able to better understand how to use the Roman system numbers, as it has rules regarding their position to be used.

The first rule to learn is that the system works with a subtractive principle. Therefore, if there are two different letters, and a smaller number comes before the larger number, subtraction must be done.

For example:

• The number 4 is represented by IV (1 and 5), which would be 5 – 1 = 4;
• For the number 9, the representation is IX (1 and 10), but according to the concept it is 10 – 1 = 9.

We should also mention that I (1) can only precede the numbers V (5) or X (10), and when it is before these numbers it cannot be repeated, that is, we will never see a number “IIV”, since it does not exist.

But beyond the subtractive, we have the additive principle also, but in this case the larger number must be on the left and decrease from there, for example:

• The number 18 in Roman numerals is XVII, which following this principle is given by the sum of 10 + 5 + 1 + 1 + 1 = 18;
• Another example would be the number 3, represented by III which is 1 + 1 + 1 = 3;
• XXVIII (28): 10 + 10 + 5 + 1 + 1 + 1 = 28.

We can also merge the two principles in some specific numbers, such as the following:

• XIV: 10 + 5 – 1 = 14;
• XXXIX: 10 + 10 + 10 – 1 = 39;
• XIX: 10 + 10 -1 = 19.

In this example, the first letter is a larger number than the second, so it must be added to the other larger number, but in the middle we have a smaller number that comes before the larger one, so it must be subtracted.

The same goes for larger numbers, like 50 or 90, see:

• XL: 50 – 10 = 40;
• XC: 100 – 10 = 90.

Another rule is that the letters I, X, C and M cannot be repeated more than 3 times, so the number 3 is represented by III and 4 by IV.

These are just some of the rules of Roman numerals to understand the basics of how to use them.

Roman numerals table

Where are Roman numerals used?

Although nowadays we use decimal number systems for basically everything, Roman numerals can still be used in specific situations.

For example, luxury or wall clocks, which can have hours and minutes represented in Roman numerals.

On some dates this numbering system can still be used, especially when we talk about centuries.

Some people often use Roman numerals in tattoos to represent a date with special meaning as well.

In older films and books we end up finding the use of Roman numerals, especially in works that have sequels.

In classic books they can also be used to number preliminary pages, such as index and introduction pages.

We can still see the use of these numbers in titles, such as that of the Pope, Kings, Queens, Princesses and other ancient leaders, as is the case with Queen Elizabeth II.

These are just a few examples of how Roman numerals are still used in various contexts today. They add a historical and stylistic element, often associated with elegance and tradition.