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.
Royal titles, such as Henry I, Henry II, and so on, use Roman numerals. Have you noticed these names and wondered what these symbols (I and II) represent? Those are Roman numerals.
Earlier people used fingers, sticks, bones, etc., for counting. When life became complex, a standard form was required to count. Ancient Romans used the Roman numeral system to count. 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 DCXLIII to represent 643. Here, D is 500, C is 100, XL is 40, and III is 3. Let’s learn more about Roman numerals and how we write them.
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 the smaller number is placed after the larger number. For example, VI → V + I → 5 + 1 = 6.
To write a large number, there are certain Roman numerals that can be repeated up to three times. For example, III → 3.
If a small number precedes a large number in Roman numerals, we subtract the smaller number from the larger one. For example, IX → X - I → 10 - 1 = 9.
The symbols cannot be repeated more than three times, and some symbols like V, L, and D cannot be repeated. For example, we won't write VV for 10; instead, we use X, and for 8, we write VIII, not IIIIIIII.
Let’s now learn how to write 643 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 643 in Roman numerals using the expansion method. To write 643 in Roman numerals, follow these steps:
Step 1: Break the number based on place value. Place values are ones, tens, hundreds, etc. For 643, we write it as 600 + 40 + 3.
Step 2: Convert the numbers into Roman numerals.
600 in Roman Numerals - DC
40 in Roman Numerals - XL
3 in Roman Numerals - III
Step 3: Combine the Roman numerals together. Therefore, 643 in Roman numerals is DC (600) + XL (40) + III (3) = DCXLIII.
When writing a large number into Roman numerals, we group the number. To write 643 in Roman numerals, we group 643 as 600 + 40 + 3.
So, 643 is written as DCXLIII in Roman numerals.
Students make mistakes when writing numbers in Roman numerals. To master Roman numerals, we can learn a few common mistakes and ways to avoid them.
If a historian discovers DCXLIII ancient coins and decides to distribute them equally among VII archaeologists, how many coins will each archaeologist receive?
Each archaeologist will receive XCII coins.
To find out how many coins each archaeologist receives, divide the total number of coins by the number of archaeologists.
DCXLIII = 643
VII = 7
643 ÷ 7 = 92
92 in Roman numerals is XCII.
An artist is creating a mural comprising of DCXLIII tiles. If each row of the mural contains XXIX tiles, how many complete rows can be formed?
XXII complete rows can be formed.
To determine how many complete rows can be formed, divide the total number of tiles by the number of tiles per row.
DCXLIII = 643
XXIX = 29
643 ÷ 29 = 22
22 in Roman numerals is XXII.
A library receives a shipment of MCMXL books, but CCCXCVII of them are damaged. How many undamaged books are there?
There are MCDXLIII undamaged books.
Subtract the number of damaged books from the total number of books to find the number of undamaged books.
MCMXL = 1940
CCCXCVII = 397
1940 - 397 = 1543
1543 in Roman numerals is MCDXLIII.
Calculate the difference between MC and DCXLIII.
The difference between MC and DCXLIII is CCCLVII.
To find the difference, subtract DCXLIII from MC.
MC = 1100
DCXLIII = 643
1100 - 643 = 457
457 in Roman numerals is CCCLVII.
Write the Roman numeral for 1000 - 357 using subtraction.
The Roman numeral for 1000 - 357 is DCXLIII.
First, calculate the result using subtraction:
1000 - 357 = 643
Then convert the result into Roman numerals: 643 in Roman numerals is DCXLIII.
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.