Roman numerals are a number system that was invented by the ancient Romans for the purpose of counting and performing other day-to-day transactions. Roman numerals use just seven letters, with the quantity and order of these letters determining the value of the final number.
These seven letters are I, V, X, L, C, D, and M and have values of 1, 5, 10, 50, 100, 500, and 1000. They can be used to write any number up to value of 3,999, which we will go into more detail about later on.
Roman numerals can look confusing to begin with, but once you have learnt to read them they are actually very easy. Let’s take a look at all the information you need to know how to read and write Roman numerals.
What Are Roman Numerals?
Roman numerals were widely used throughout Europe as the standard writing system until the late middle ages. It is thought that the Romans started using them because they figured that once a number reaches 10 it becomes very hard to count on your fingers.
Roman numerals use seven letters to represent different numbers. These are I, V, X, L, C, D, and M which hold the integer values of 1, 5, 10, 50, 100, 500, and 1000 respectively. The frequency and position of these letters determines the value of the final number. There are a few different rules when writing Roman numerals, but once they are understood Roman numerals can be easy to read.
Roman numerals have been used from around the 8th to 9th century BC, and are still used today. Today we use Western Arabic numerals (0, 1, 2, 3, 4, 5, 6, 7, 8 and 9), which became widely known during the 15th century, but can still find Roman numerals on clock faces, in movie titles, and in many other areas.
How Do You Read Roman Numerals?
Roman numerals are written through a combination of seven letters. These are as follows:
In order to write a number, Roman numerals can be used by combining letters together. This is almost like a small math problem that needs to be solved, but is much simpler than it seems. For example, the number 23 is much easier to write with a few different letters, instead of 23 “I” letters!
No More Than Four In A Row and the Subtractive Principle
If I = 1, then II = 2 and III = 3. So, four would be IIII, right? Actually, this isn’t the case.
Romans didn’t like having four of the same letter in a row. If you were trying to write the letter nine just using “1”, you’d have to write out nine “I”s, which could get confusing to count and take much longer.
Therefore, the Romans came up with the subtractive principle. Let’s take a look at the number four again. In Roman numerals, four is actually written as IV.
I = 1 and V = 5. So effectively what the number IV is saying, is that it is five minus one.
Another example is the number nine. Instead of being written VIIII (which is 5 + 1 + 1 + 1 + 1), it is written as IX. X = 10 and I = 1, so IX is ten minus one.
Now you’ve grasped the basis of the subtractive principle, it’s important you understand which order the letters need to be written. While IX = 9, XI does not equal 9. So the order in which you write them is important to get right.
The simple way to explain this, is that the number needs to be subtracted if it appears before a larger one.
Looking at number nine again (IX), we can see that the I (1) comes before X (10). So these letters are telling you that the I needs to be subtracted from the X. So, 10 minus 1 equals 9.
While this is an easy principle to follow with small numbers it can get more confusing with large numbers. An example is the number 39.
XXXIX = 39. Take a look at the Roman numeral chart above and see if you can work out why.
The explanation goes as follows.
X = 10, so XXX = 30. We are then left with IX. We know that I = 1, and we also know that if it comes before an X, we need to subtract it, so IX = 9. Therefore, our whole number (XXXIX) must equal 39.
But what if the smaller number comes after the bigger? You might have guessed, but the the number needs to be added if it appears after a larger one.
So, if IX = 9, what does XI equal?
X = 10 and I = 1, and with the I coming after the X, we need to add them together. Therefore XI = 11.
The same goes if we look at larger numbers. For example XXXII = 32.
X = 10, so XXX = 30. We are then left with II, which come after the X, so therefore need to be added. II = 2, so XXXII = 32.
A Limited Number Of Letters
Because there are only 7 letters, there are only six instances in which the smaller number will need to be subtracted from the larger. These are:
- I (1) before V (5) or X (10)
- X (10) before L (50) or C (100)
- C (100) before D (500) or M (1000)
For example, the number forty is written as XL. X = 10 and L = 50. We can’t write forty as XXXX because Roman’s do not like four of the same letters in a row, so instead we write is as XL, showing us that the X (10) needs to be subtracted from the L (50).
Something else we should mention is that L, V, D cannot be repeated or the number is considered to be invalid. This is because there are already letters that represent double of these letters. For example, L = 50. Therefore LL = 100, but there is already a letter for 100 (C).
Numbers Over 4,000
The number 4,000 cannot be written in regular Roman numerals. This is because it would need to be written MMMM, and this goes against the rule of no more than three letters of the same in a row. So, do Roman numerals only go up to 3,999?
To write numbers over 4,000, Romans had to use a vinculum. A vinculum is a line above the letters, which represents a multiple of 1,000. It could cover the whole or just the beginning part of a number. Take a look at some of the examples below.
It is often debated as to whether Romans actually used a vinculum or whether it was introduced later. Because Roman’s primarily used their number’s for trade, it was unlikely they needed a number over 3,999. No one is going to be buying 4,000 loaves of bread! They had much less to buy back then in comparison to today.
Below is the complete Roman numerals chart from 1 to 100, so you can explore what we just discovered above.
|No.||Roman Numeral||No.||Roman Numeral||No.||Roman Numeral||No.||Roman Numeral||No.||Roman Numeral|
When Did Arabic Numerals Take Over?
Nowadays, we don’t use Roman numbers in every day life, but instead use Arabic numerals. Arabic numerals are the ten numerical digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. They allow us to write decimal numbers. They are also called Western Arabic numerals.
Arabic numbers were introduced to Europe in the tenth century by Arabic speakers of Spain and North Africa, who were then using the digits from Libya to Morocco. The first mentions of the numerals in the West are found in the Codex Vigilanus (aka Albeldensis) of 976.
The European acceptance of the numerals was accelerated by the invention of the printing press, and they became widely known during the 15th century. In central Europe, the King of Hungary, Ladislaus the Posthumous, started the use of Arabic numerals, which appear for the first time in a royal document of 1456, and by the mid-16th century, they were in common use in most of Europe.
Other Numerical Systems
There have been many numerical systems used throughout the world throughout the last thousands of years. Aside from the Arabic and Roman numeral systems, you may also be familiar with Egyptian numerals, Chinese numerals, Greek numerals and Japanese numerals.
What Are Modern Uses Of Roman Numerals?
Despite being slightly more confusing that Arabic numerals, Roman numerals are still used today in a number of ways. You may not even realize that you see Roman numerals on a day to day basis!
The most common way in which Roman numerals are used today is on clocks and watch faces. However, they are also sometimes used in movie or video game titles (such as Rocky II or Grand Theft Auto V), when naming monarchs (George III or Elizabeth II), and also on old buildings or landmarks.
Another use of Roman numerals is for the copyright date on movies and TV shows. Can you guess how 2022 would be written? MMXXII!
Roman Numeral FAQs
Was 4,000 the highest number Roman’s could count to?
The highest number that can be expressed in Roman numerals is actually 3,999. This is written as MMMCMXCIX. This is because the number 4,000 would have to be written as MMMM, which goes against the principle of not having four consecutive letters of the same type together.
How do you write 0 in Roman numerals?
The number zero was not really featured by the Romans simply because they had little use for it. This is because Roman numerals were used for buying and trading, and no one needed 0 loaves of bread at the market!
If you wondering how Romans would write a number with a zero in, for example the number 203, they would just do this like any other number. Take a look at the chart at the top of this page and see if you can work out how they would write 203.
C = 100, so CC = 200.
I = 1, so III = 3.
So, 203 = CCIII.
As you can see, there is no need for the number 0 in Roman numerals!
What about the Roman alphabet?
There are 23 letters in the Roman alphabet, compared to our 26, and they would use them just like we do. The fact that they also use certain letters to represent numbers does not change how they use their letters when writing words.
The 23 letters in the Roman alphabet are A, B, C, D, E, F, G, H, I, K, L, M, N, O, P, Q, R, S, T, V, X, Y and Z.
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Link will appear as Hanson, Marilee. "Roman Numerals" https://englishhistory.net/romans/roman-numerals/, May 10, 2022