What are Roman Numerals?
At first, the Roman numbers were pictograms. Then, they became similar to what we now know as Latin script.
History of Roman Numerals
As the Roman Empire grew and took in all of Europe, the numerals incorporated some Greek mathematical concepts. And with them, the letters that meant one thousand and one hundred. Some even suggest they may have copied the letter for fifty as well.
The first five Roman numerals
Just like the Chinese, Romans used a line to represent a single unit. But unlike their Asian counterparts, they used a vertical line.
Because they used fingers to count.
To this day, Italians use their fingers in a precise way when expressing numbers. They lift the index finger—in some regions, the thumb—to start counting.
Two and Three
Stretching the index finger equals one. For two, you need to extend the middle finger. And to represent three, you point the thumb outwards.
For Romans, the thumb also meant Yay or Nay, depending on the direction it points out.
Today, some Italians may start counting by stretching their thumb. In that case, the order would be the thumb, index, and middle finger. Roman numerals depict the same scene by adding vertical lines.
Four and Five
To understand how Romans wrote the number four, we need to look at the number five first.
Just like the previous numbers, another gesture points to its meaning.
Have you ever raised your hand to attract someone’s attention?
The gesture is the same most people make when signaling a waiter. With the thumb and index finger out, the hand looks like gesticulating the letter V.
Over time, the symbol for five became the letter V. However, the fourth Roman numeral is IV. The reason is that by putting an index finger in front of the other hand, they could signal the number four from great distances. In other words, IV means one less than five.
Romans were soldiers, and they fought in battalions. In other words, they needed a reliable way to communicate on the battlefield. Also, they could not count on modern binoculars. So, they developed numbers that were easy to reproduce and understand from far away.
Number Position and Order
Romans used the same method to write the remaining numbers.
Here are the rules for creating Roman numerals:
- You can only place one line before a greater number to indicate that it is one unit less. In the same way, you can use some symbols to subtract from bigger units as long as the overall method maintains its logic. More on this later.
- The first letter can only be followed by a lesser numeral or a letter that represents a smaller number.
- As Romans did not use spaces or commas in writing, if you read a character bigger than the one that comes next, the author must have listed another number.
- Just like with the vertical lines, you cannot repeat a symbol more than three times in a row.
You just learned to count up to eight in the Roman numeral system!
Given these rules, you now know that you can only write numbers like 9, 14, 19, etc. by placing a vertical line before the letter that equals the following unit.
Similarly, you learned how to write three other numbers by adding vertical lines after the V. You can also understand why Romans added more letters to avoid confusion when writing numbers like 10, 15, and so on.
Other Symbols in the Roman Numerical Notation
Nine and Ten
The letter for ten is X. If you think about it, you will soon realize that an X is nothing more than two letters V stacked upon one another. Of course, one is upside down.
As the previous rules explained, we can add a vertical line to write 9. So, nine is IX.
Romans kept using the same method to write all the numbers up to 50. They would double and triple the X to write numbers up to 39. But then, they reached a plateau.
At first, they drew a vertical line across the middle of the letter V to represent the number 50. They got this idea from the Greek letter psi (Ψ). But soon, usage morphed from a mix of the vertical line and the V to a more stylized form that later became the letter L.
Using an L was more practical. Also, it allowed for writing forty, which is ten less than fifty. That is, XL.
One Hundred, Five Hundred, And One Thousand
The Latin word for one hundred was centum. And the letter for the same figure is C. However, the two are not related.
As surprising as it may sound, the letter C is the lazy representation of the Greek letter theta (θ). Some scholars believe that the Romans had to use half of it because of another reason. That is, the Greek letter phi (Φ), which the Greeks used to write several numbers depending on where they put an apex.
In any case, the Romans started using the letter phi to write One Thousand. But at one point, they changed it into CIƆ. The number one thousand was the only one that required three characters. As you can imagine, that sparked confusion. So, the writers started connecting the three letters.
The first C slanted over the I in the middle. In the same fashion, the backward C leaned back toward the I.
This is why we now have the letter M!
Using the Roman Numeral D for 500
The letter D for 500 has a comparable origin as the M for 1,000. This letter was born because the letter D is what you get when you connect the I in the middle of CIƆ to the backward C.
The Romans thought of getting rid of the first C to halve the number One Thousand. Of course, this choice also avoided any mistakes. Often, the sculptor would carve the letter I and backward C deeply to prevent confusion. So, forming a new letter proved to be a more effective way to speed up the writing on stones and tablets without losing any meaning.
Roman Numerals Summary:
- The upper case letter I represent Arabic 1.
- The upper case letter V represents the Arabic 5.
- The upper case letter X represents the Arabic 10.
- The upper case letter L represents the Arabic 50. (not used in this document)
- The upper case letter C represents the Arabic 100. (not used in this document)
- The upper case letter D represents the Arabic 500. (not used in this document)
- The upper case letter M represents the Arabic 1,000. (not used in this document)
- A bar placed over a letter or group of letters multiplies that value by 1,000. (not used in this document)
- If the letter to the right represents an equal or smaller value the numbers ADD. XXII is 22.
- If the letter to the right is a larger value than the numbers SUBTRACT. IV is 4. Only I is used with V or X, X with L or C, and C with D or M.
- There is no zero!
- Both C and M often still appear in commerce mixed with Arabic therefore if someone orders a quantity of 5M, they want 5,000 not 5 million.
- A few more samples: XCV = 95, XIII = 13, XCIX = 99, XLIX = 49
Roman Numerals Chart
The following is a Roman Numerals Chart showing the Roman Numerals in order:
|1 in Roman Numerals||I|
|2 in Roman Numerals||II|
|3 in Roman Numerals||III|
|4 in Roman Numerals||IV|
|5 in Roman Numerals||V|
|6 in Roman Numerals||VI|
|7 in Roman Numerals||VII|
|8 in Roman Numerals||VIII|
|9 in Roman Numerals||IX|
|10 in Roman Numerals||X|
|11 in Roman Numerals||XI|
|12 in Roman Numerals||XII|
|13 in Roman Numerals||XIII|
|14 in Roman Numerals||XIV|
|15 in Roman Numerals||XV|
|16 in Roman Numerals||XVI|
|17 in Roman Numerals||XVII|
|18 in Roman Numerals||XVIII|
|19 in Roman Numerals||XIX|
|20 in Roman Numerals||XX|
|21 in Roman Numerals||XXI|
|22 in Roman Numerals||XXII|
|23 in Roman Numerals||XXIII|
|24 in Roman Numerals||XXIV|
|25 in Roman Numerals||XXV|
|26 in Roman Numerals||XXVI|
|27 in Roman Numerals||XXVII|
|28 in Roman Numerals||XXVIII|
|29 in Roman Numerals||XXIX|
|30 in Roman Numerals||XXX|
|31 in Roman Numerals||XXXI|
|32 in Roman Numerals||XXXII|
|33 in Roman Numerals||XXXIII|
|34 in Roman Numerals||XXXIV|
|35 in Roman Numerals||XXXV|
|36 in Roman Numerals||XXXVI|
|37 in Roman Numerals||XXXVII|
|38 in Roman Numerals||XXXVIII|
|39 in Roman Numerals||XXXIX|
|40 in Roman Numerals||XL|
|41 in Roman Numerals||XLI|
|42 in Roman Numerals||XLII|
|43 in Roman Numerals||XLIII|
|44 in Roman Numerals||XLIV|
|45 in Roman Numerals||XLV|
|46 in Roman Numerals||XLVI|
|47 in Roman Numerals||XLVII|
|48 in Roman Numerals||XLVIII|
|49 in Roman Numerals||XLIX|
|50 in Roman Numerals||L|
|51 in Roman Numerals||LI|
|52 in Roman Numerals||LII|
|53 in Roman Numerals||LIII|
|54 in Roman Numerals||LIV|
|55 in Roman Numerals||LV|
|56 in Roman Numerals||LVI|
|57 in Roman Numerals||LVII|
|58 in Roman Numerals||LVIII|
|59 in Roman Numerals||LIX|
|60 in Roman Numerals||LX|
|61 in Roman Numerals||LXI|
|62 in Roman Numerals||LXII|
|63 in Roman Numerals||LXIII|
|64 in Roman Numerals||LXIV|
|65 in Roman Numerals||LXV|
|66 in Roman Numerals||LXVI|
|67 in Roman Numerals||LXVII|
|68 in Roman Numerals||LXVIII|
|69 in Roman Numerals||LXIX|
|70 in Roman Numerals||LXX|
|71 in Roman Numerals||LXXI|
|72 in Roman Numerals||LXXII|
|73 in Roman Numerals||LXXIII|
|74 in Roman Numerals||LXXIV|
|75 in Roman Numerals||LXXV|
|76 in Roman Numerals||LXXVI|
|77 in Roman Numerals||LXXVII|
|78 in Roman Numerals||LXXVIII|
|79 in Roman Numerals||LXXIX|
|80 in Roman Numerals||LXXX|
|81 in Roman Numerals||LXXXI|
|82 in Roman Numerals||LXXXII|
|83 in Roman Numerals||LXXXIII|
|84 in Roman Numerals||LXXXIV|
|85 in Roman Numerals||LXXXV|
|86 in Roman Numerals||LXXXVI|
|87 in Roman Numerals||LXXXVII|
|88 in Roman Numerals||LXXXVIII|
|89 in Roman Numerals||LXXXIX|
|90 in Roman Numerals||XC|
|91 in Roman Numerals||XCI|
|92 in Roman Numerals||XCII|
|93 in Roman Numerals||XCIII|
|94 in Roman Numerals||XCIV|
|95 in Roman Numerals||XCV|
|96 in Roman Numerals||XCVI|
|97 in Roman Numerals||XCVII|
|98 in Roman Numerals||XCVIII|
|99 in Roman Numerals||XCIX|
|100 in Roman Numerals||C|