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, use Roman numerals. Have you noticed the names and wondered what these symbols (I and II) represented? Those are Roman numerals.
Earlier, people used fingers, sticks, bones, etc., to count. When life became 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 we use to count.
In Roman numerals, we use CXLV to represent 145, where C is 100, XL is 40, and V is 5. Let’s learn more about Roman numerals and how we write them.
CXL = 100 + 40 = 140 CXLI = 100 + 40 + 1 = 141 CXLII = 100 + 40 + 2 = 142 CXLIII = 100 + 40 + 3 = 143 CXLIV = 100 + 40 + 4 = 144 CXLV = 100 + 40 + 5 = 145
There are certain basic rules to write a number in Roman numerals. In this section, let’s discuss some basic rules that need to be remembered when writing a number in Roman numerals.
The addition method is used when a smaller number is placed after a larger number. For example, XV → X + V → 10 + 5 = 15.
To write a larger number, certain Roman numerals can be repeated up to three times. For example, CCC → 300.
If a small number is followed by a larger number in Roman numerals, we subtract the smaller number from the larger number. For example, XL → L - X → 50 - 10 = 40.
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 CCCCC for 500; instead, we use D.
Let’s now learn how to write 145 in Roman numerals. Follow these methods to write the number in Roman numerals.
In the expansion method, based on place value, the number is broken down. In this section, we will learn how to write 145 in Roman numerals using the expansion method.
To write 145 in Roman numerals, follow the steps:
Step 1: Break the number based on place value. Place values include ones, tens, hundreds, etc.
For 145, we write it as 100 + 40 + 5.
Step 2: Convert the numbers into Roman numerals:
100 in Roman numerals — C
40 in Roman numerals — XL
5 in Roman numerals — V
Step 3: Combine the Roman numerals together.
Therefore, 145 in Roman numerals is C (100) + XL (40) + V (5) = CXLV.
When writing a large number into Roman numerals, we group the number. To write 145 in Roman numerals, we group 145 as 100 + 40 + 5.
100 in Roman numerals — C
40 in Roman numerals — XL
5 in Roman numerals — V
So, 145 is written as CXLV in Roman numerals.
Students make mistakes when writing a number in Roman numerals. To master Roman numerals, we can learn a few common mistakes and the ways to avoid them.
A historian finds a document stating that the population of a small village was CXXXV in the year XCV. If the population grew by X in the next year, what was the new population?
The new population was CXLV.
The original population is CXXXV, which is 135.
Increased by X, which is 10.
135 + 10 = 145.
145 in Roman Numerals is CXLV.
A library has DCCCXLV books and wants to distribute them equally among V pupils. How many books will each pupil receive?
Each pupil will receive CLXIX books.
To find the number of books each pupil gets, divide the total number of books by the number of pupils.
DCCCXLV = 845
V = 5
845 / 5 = 169
169 in Roman Numerals is CLXIX.
Calculate the difference between CCXLV and C in Roman numerals.
The difference is CXLV.
The difference between two numbers is found by subtracting one from the other.
CCXLV = 245
C = 100
245 - 100 = 145
145 in Roman Numerals is CXLV.
A teacher has a total of CCLXX notebooks and wants to give an equal number of notebooks to each of the XVIII students. How many notebooks will each student receive?
Each student will receive XV notebooks.
To find the number of notebooks each student receives, divide the total number of notebooks by the number of students.
CCLXX = 270
XVIII = 18
270 / 18 = 15
15 in Roman Numerals is XV.
Write the Roman Numeral for the result of multiplying IX by XVI using the expansion method.
The result of IX multiplied by XVI is CXLIV.
Step 1: Convert the numbers IX and XVI into Roman numerals.
IX = 9
XVI = 16
Step 2: Multiply the numbers:
9 × 16 = 144
Step 3: Use the expansion method:
144 = 100 + 40 + 4 = CXLIV
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.