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 these symbols and wondered what they represent? These are Roman numerals.
Earlier, people used fingers, sticks, bones, etc., to count. As life became more complex, a standardized form was required. Ancient Romans developed the Roman numeral system. I (1), V (5), X (10), L (50), C (100), D (500), and M (1000) are the symbols used to count.
In Roman numerals, 423 is written as CDXXIII. Here, CD is 400, XX is 20, and III is 3. 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 rules to keep in mind when writing a number in Roman numerals.
The addition method is used when a smaller number is placed after a larger number for addition. For example, XII → X + I + I → 10 + 1 + 1 = 12.
Some Roman numerals can be repeated up to three times. For example, III → 3.
If a smaller number precedes a larger number, it is subtracted from the larger number. For example, IX → X - I → 10 - 1 = 9.
Symbols cannot be repeated more than three times, and some symbols, like V, L, and D, cannot be repeated. For example, we write 10 as X, not VV.
Let’s now learn how to write 423 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 423 in Roman numerals using the expansion method. To write 423 in Roman Numerals, follow the steps:
Step 1: Break down the number based on place value: hundreds, tens, and ones. For 423, we write it as 400 + 20 + 3.
Step 2: Convert each part into Roman numerals.
400 in Roman Numerals - CD
20 in Roman Numerals - XX
3 in Roman Numerals - III
Step 3: Combine the Roman numerals together. Therefore, 423 in Roman Numerals is CD (400) + XX (20) + III (3) = CDXXIII.
When writing a large number in Roman numerals, we group the number. To write 423 in Roman numerals, we group it as 400 + 20 + 3.
So, 423 is written as CDXXIII in Roman numerals.
Students often make mistakes when writing numbers in Roman numerals. To master Roman numerals, we can learn from common mistakes and the ways to avoid them.
A historian found a treasure map indicating that CDXXIII gold coins are buried under the old oak tree. How many more coins would you have if you found an additional LXXVII coins nearby?
You would have D coins in total.
First, convert the Roman numeral CDXXIII to its equivalent number: 423.
Then, convert LXXVII to its equivalent number: 77.
Add the numbers together: 423 + 77 = 500. 500 in Roman Numerals is D.
A marathon had CDXXIII participants, but only half of them finished the race. How many participants completed the marathon?
The number of participants who completed the marathon is CCXI.
To find the number of participants who completed the marathon, divide the total participants by 2.
CDXXIII = 423, so 423 / 2 = 211.5.
Since participants must be whole numbers, assume approximately 211 finished. 211 in Roman Numerals is CCXI.
A collector has a portfolio of CDXXIII rare stamps and decides to sell CXLIV of them. How many rare stamps does the collector have left?
The collector has CCLXXIX rare stamps left.
Subtract the number of stamps sold from the total collection:
423 - 144 = 279
Convert 279 to Roman Numerals: 279 = CCLXXIX.
An ancient manuscript refers to a sum of CDXXIII and XCIX. Find this sum in Roman Numerals.
The sum of CDXXIII and XCIX is DXXII.
First, convert CDXXIII and XCIX to their numeric equivalents: 423 and 99.
Then, add them together: 423 + 99 = 522.
Convert 522 to Roman Numerals: 522 = DXXII.
Write the Roman Numeral for the difference between CDXXIII and CLX using the subtraction method.
The Roman Numeral for the difference is CCLXIII.
First, convert CDXXIII and CLX to numbers: 423 and 160. Subtract the numbers:
423 - 160 = 263
Convert 263 to Roman Numerals using the subtraction method: 263 = CCLXIII.
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.