Last updated on May 26th, 2025
In ancient Rome, letters were used to define numbers. This made their calculations easy. Even today, Roman numerals are popular everywhere. They are used to indicate royalty, book serial numbers, or clock faces. This article will teach you everything that you need to know about Roman numerals.
In Roman numerals, the symbol 'XXXIII' is used to represent 33. Mentioned below are the seven symbols used in the ancient numeric system:
I - 1
V - 5
X - 10
L - 50
C - 100
D - 500
M - 1000
According to the symbols given above, XXXIII represents 33. As you can see, the number 0 does not appear anywhere in this numeric system. Let us now see the basic rules to write Roman numerals
Rule 1: Addition Method — In the addition method, you will combine different Roman numerals. When a smaller or the same number is placed after the larger number, we will simply add it -V(5) + I (1) = VI(6)
Rule 2: Repetition Method — In this method, a Roman numeral can only be used up to 3 times to get a larger value
I + I + I = III (3)
X + X + X = XXX (30)
But we can’t write XXXX for 40, it's XL (40)
Rule 3: Subtraction Method — In the above repetition method, we got to know that a symbol can’t be used more than 3 times, then how will we write 40? Here, we will use the subtraction method. If the smaller numeral is placed before the larger numeral, then you have to subtract the smaller numeral from the larger numeral. For example, if we take XL (40), the smaller numeral X (10) is subtracted from the larger numeral L (50). So, L (50) - X (10) = XL (40).
Rule 4: Limitation Rule - We can't repeat a number more than 3 times in Roman numerals. Instead of that, we will add and subtract. E.g. 4 is not to be written as IIII, instead write IV (subtraction method, i.e., 5-1=4). For ten (X), we can't use VV, as we have a specific letter for each value. For example, (V = 5, X = 10, L = 50, C = 100, D = 500, and M = 1000). As you can see, we have to use these symbols for specific values. Roman numeric system can be used easily by following these rules.
To write 33 in Roman numerals, we can simply write it using the symbol XXXIII. It can be done using two methods :
Expansion Method: In this method, we will break the Roman numeral in smaller parts based on their values and then add them. Here, XXVIII (28) is made up of 2 parts that are 20 and 8. 20 can be written as XX which can also be written as X + X. 8 can be written as VIII which can also be written as V + III. Now if we add it, X + X + V + III = 28.
Grouping method - We look at the numerals l and group them based on the rules of addition, subtraction, and repetition. We then add them together. Example, XIV
X - 10, IV - 4 (since I came before V, we subtract 1 from 5).
The method is about breaking the numbers according to the place values. Here are the steps for a better understanding.
Breaking down place values such as hundreds and tens.
We are going to represent the value with a Roman numeral.
Now, we will add those values together to reach the right numerals.
For instance,
XLIX: X = 10
L = 50
IX = 9
We can represent this as,
XL = 50 - 10 = 40
IX = 10 - 1 = 9
So the expansion of XLIX is
40 + 9 = 49
In Roman numerals, large numbers are expressed through grouping methods. Here are a few grouping methods shown below:
So we determine which Roman numerals are going to be added and which are going to be subtracted.
Add or subtract the symbols of the smaller numerals.
Then just add these values to represent the desired Roman numeral.
For instance, XLIX:
XLIX = 49
XL = 50 - 10 = 40
IX = 10 - 1 = 9
Here we add: 40 + 9 = 49.
Combinations of numerals that represent specific values are what the grouping method focuses on.
While learning Roman numerals, it is common to make mistakes. By understanding these mistakes, you can avoid them when you read or write Roman numerals.
Write the factors of 33 in Roman numerals.
The factors of 33 in Roman numerals are I, III, XI, XXXIII
First identify the factors of 33. The factors of 33 are 1, 3, 11, and 33.
Therefore, the factors of 33 in Roman numerals are I, III, XI, XXXIII
What will be the sum when XXXIII is added to 7? Write the sum in words.
The sum is 40. Number 40 in words is ‘forty’
The value of XXXIII is 33 and when 7 is added to it, we get 40 as the sum. We write 40 in words as ‘forty’
Calculate C-XXXIII and check if it's a multiple of 5
The result is 67 and it is not a multiple of 5
The values for C and XXXIII are 100 and 33, respectively. When 33 is subtracted from 100, we get 67 as the result. Since the last digit of 67 is 7, we can say that it is not a multiple of 5
XL is written as 40. Here, X is written before L, where X represents 10 and L represents 50
The smaller number (X) is placed before the larger number (L). So we subtract it from the larger number L (50) - X(10) = 40 (XL)
Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.
: She loves to read number jokes and games.