Last updated on May 26th, 2025
Roman numerals are a way of expressing numbers using symbols. I, V, X, L, C, D, and M are the symbols we use. Roman numerals are used in royal titles, book names, sequences, and so on. Here we will be discussing Roman numerals, rules, and examples.
The royal titles, such as Henry I, Henry II, and so on, often use Roman numerals. Have you noticed these names and wondered what these symbols (I, II) represent? Those are Roman numerals.
In ancient times, people used to count using fingers, sticks, bones, etc. As life became more complex, a standard form was required to count. Ancient Romans used the Roman numeral system for this purpose. I (1), V (5), X (10), L (50), C (100), D (500), and M (1000) are the symbols used for counting.
In Roman numerals, we use CLXXII to represent 172, where C is 100, L is 50, XX is 20, and II is 2. Let’s learn more about Roman numerals and how we write them.
There are certain basic rules for writing numbers in Roman numerals. In this section, let’s discuss some basic rules that need to be remembered when writing numbers in Roman numerals.
Rule 1: Addition Method
The addition method is used when a smaller number is placed after a larger number. For example, CLXXII → C + L + XX + II → 100 + 50 + 20 + 2 = 172
Rule 2: Repetition Method
To write larger numbers, certain Roman numerals can be repeated up to three times. For example, XX → 20.
Rule 3: Subtraction Method
If a smaller number precedes a larger number in Roman numerals, the smaller number is subtracted from the larger number. For example, IX → X - I → 10 - 1 = 9
Rule 4: Limitation Rule
The symbols cannot be repeated more than three times, and some symbols like V, L, and D cannot be repeated. For example, we don't write LL for 100; instead, we use C.
Let’s now learn how to write 172 in Roman numerals. Follow these methods to write the number in Roman numerals.
In the expansion method, based on the place value, the number is broken down. In this section, we will learn how to write 172 in Roman numerals using the expansion method.
Step 1: Break the number based on the place value. Place values are ones, tens, hundreds, etc.
For 172, we write it as 100 + 50 + 20 + 2.
Step 2: Convert the numbers into Roman numerals.
- 100 in Roman numeral — C
- 50 in Roman numeral — L
- 20 in Roman numeral — XX
- 2 in Roman numeral — II
Step 3: Combine the Roman numerals together.
Therefore, 172 in Roman numerals is C (100) + L (50) + XX (20) + II (2) = CLXXII.
When writing large numbers in Roman numerals, we group the numbers. To write 172 in Roman numerals, we group 172 as 100 + 50 + 20 + 2.
- 100 in Roman numeral — C
- 50 in Roman numeral — L
- 20 in Roman numeral — XX
- 2 in Roman numeral — II
So, 172 is written as CLXXII in Roman numerals.
Students make mistakes when writing numbers in Roman numerals. To master Roman numerals, we can learn a few common mistakes and the ways to avoid them.
A historian is cataloging ancient artifacts labeled CLXXII and XXV. What is the total number of artifacts?
The total number of artifacts is CXCVII.
To find the total, we add the two numbers.
CLXXII = 172
XXV = 25
172 + 25 = 197
197 in Roman Numerals is CXCVII.
A librarian has a collection of CCCXLIV manuscripts and wants to distribute them equally into II groups. How many manuscripts will each group receive?
Each group will receive CLXXII manuscripts.
To determine the number of manuscripts per group, we divide the total number by the number of groups.
CCCXLIV = 344
II = 2
344 / 2 = 172
172 in Roman numerals can be written as CLXXII.
Combine the value of CLXXII with XXXVIII and express the result in Roman numerals.
The combined value is CCX.
To find the sum, add the two numbers.
CLXXII = 172
XXXVIII = 38
172 + 38 = 210
210 in Roman Numerals is CCX.
Determine the difference between CC and CLXXII.
The difference between CC and CLXXII is XXVIII.
The difference is found by subtracting the smaller number from the larger number.
CC = 200
CLXXII = 172
200 - 172 = 28
28 in Roman Numerals is XXVIII.
Convert 172 into Roman numerals using the expansion method.
CLXXII
Break down the number 172:
100 + 70 + 2
100 = C
70 = LXX
2 = II
Combine them to get CLXXII.
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.