- On 2016-07-02
- By Edugain
Roman number system is one of the ancient counting and calculating methods. Used in the period between 9th century BC to 2nd century AD, they served us with one of the most complicated methods to count, especially when it comes to larger numbers.
Now an interesting question arises: Why do we learn Roman Numerals?
As the generation of today, we still learn Roman Numerals to find that many generations ago, people used counting methods that were far more complicated than the methods we use today. Knowing Roman Numerals helps us appreciate the Decimal Number System in use today. The fact that the decimal number system can empower us to do far more complicated calculations than Roman numerals encourages us to always strive to find newer and better ways to do what we do everyday. Such endeavours make newer generations smarter than the old ones.
Well, there are other practical reasons to learn Roman numerals too:
- They are frequently used in watches.
- Many major sports events like the Olympics still use Roman Numerals, e.g. 2008 Olympics that took place in Beijing were XXIX Olympiad and the 2012 Games held in London were XXX Olympiad.
- Major Historical events are still denoted using the Roman numerals, e.g. World War I, World War II, Battle of Panipat III, etc.
- While writing documents or books, we still use Roman numerals for enumerating sections or chapters. For example, Chapter I, Chapter II etc
Learning basics of Roman Numerals adds a lot to our understanding and knowledge. So, let’s do that now!
Basic symbols to write Roman Numerals
The Roman Numeral system has basic letter symbols for the following numbers:
1 = I, 5 = V, 10 = X, 50 = L, 100 = C, 500 = D and 1000 = M.
Yes that's all we have -- 7 basic letter symbols to represent 7 different numbers. All the other numbers can be formed using these seven symbols. Seems kind of magical, doesn’t it? Well, let’s learn more to see how it is possible.
Rules to form Roman numerals using symbols
While we have 7 different symbols to mean seven different numbers, there are certain rules to group them together to form other numbers. Let’s take a look at them:
- Repetition Rules
Repetition of a Roman numeral means addition.
For example: X means 10, so XX will mean 20 and XXX will mean 30.
Only I, X, C and M can be repeated. V, L and D can never be repeated.
For example, V means 5, but we can not write VV to convey 10. It is against the rules!
No symbol can be repeated more than three times.
For example, we can not write XXXX to convey 40.
- Repetition of a Roman numeral means addition.
Rules of Addition and Subtraction of numerals
A smaller numeral written to the right of a larger numeral is always added to the larger numeral.
For example, X means 10 and V means 5. XV will then mean 10 + 5 = 15.
A smaller numeral written to the left of a larger numeral is always subtracted from the larger numeral.
For example, C means 100 and X means 10. XC will then mean 100 - 10 = 90.
V, L and D are never subtracted.
For example, we can not write VL to mean 50 - 5 = 45. This is against the rules!
When a smaller numeral is placed between two larger numerals , then it is always subtracted from the larger numeral immediately following it.
For example, this is what we should do to find the meaning of XIV. Subtract the value of I
from the value of V and then add what you get to the value of 10:
- First get 5 - 1 = 4.
- Then add 4 to the value of X: 10 + 4 = 14.
Only a single symbol can be subtracted from another single symbol. Subtraction can not be done with groups of symbols.
For example, while writing VII is correct to say 5 + 1 + 1 = 7, it is incorrect to write IIX to say 10 - (1 + 1) = 8.
A symbol can not be subtracted from another one that is more than 10 times greater than it.
- We can not write IL to convey 50 - 1 = 49 because L (50 ) is 50 times I (1).
- We can not write LM to convey 1000 - 50 = 950 because M (1000) is 20 times L (50).
- A smaller numeral written to the right of a larger numeral is always added to the larger numeral.
You must be wondering how would we write numbers greater than 3000. If we put a bar over a symbol, its value gets multiplied by 1000. For example:
5000 = V
10000 = X
50,000 = L
100,000 = C
We never reach that far in Roman Numeral system in our academic curriculum though!
As we told you in the beginning, rules to form Roman numerals can get complex. Always writing Roman numerals correctly will require some practice. With Edugain, you can download unlimited worksheets on Roman numerals, or practice online till you have perfected them. Practice Roman numerals now.