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 used. 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, often use Roman numerals. These symbols (I and II) represent numbers. Earlier, 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 to count. 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 CXXVIII to represent 128, where C is 100, XX is 20, and VIII is 8. Let’s learn more about Roman numerals and how we write them.
There are certain basic rules for writing 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.
Rule 1: Addition Method
The addition method is used when the smaller number is placed after the larger number. For example, VIII → V + I + I + I → 5 + 1 + 1 + 1 = 8.
Rule 2: Repetition Method
To write a large number, certain Roman numerals can be repeated up to three times. For instance, XXX → 30.
Rule 3: Subtraction Method
If a smaller number precedes a larger number in Roman numerals, we subtract the smaller number 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 won't write VV for 10; instead, we use X, and 8 is written as VIII, not IIIIIIII.
Let’s now learn how to write 125 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 128 in Roman numerals using the expansion method.
To write 128 in Roman numerals, follow these steps:
Step 1: Break the number based on the place value into hundreds, tens, and ones.
For 128, we write it as 100 + 20 + 8.
Step 2: Convert each component into Roman numerals.
100 in Roman numerals is C.
20 in Roman numerals is XX.
8 in Roman numerals is VIII.
Step 3: Combine the Roman numerals together.
Therefore, 128 in Roman numerals is C (100) + XX (20) + VIII (8) = CXXVIII.
When writing a large number in Roman numerals, we group the numbers. To write 128 in Roman numerals, group 128 as 100 + 20 + 8.
100 in Roman numerals is C.
20 in Roman numerals is XX.
8 in Roman numerals is VIII.
So, 128 is written as CXXVIII in Roman numerals.
Students often make mistakes when writing numbers in Roman numerals. To master Roman numerals, we can learn a few common mistakes and ways to avoid them.
A historian is analyzing ancient manuscripts and finds that the value of a scroll is written as CXXVIII. The historian finds another scroll valued at LXXX. What is the total value of both scrolls in Roman numerals?
The total value of both scrolls is CCVIII.
The values of the scrolls are CXXVIII = 128 and LXXX = 80. Adding them gives 128 + 80 = 208. The Roman numeral for 208 is CCVIII.
A merchant has a stockpile of CXLVIII gemstones. After selling XX gemstones, how many gemstones does the merchant have left?
The merchant has CXXVIII gemstones left.
The merchant originally has CXLVIII = 148 gemstones. After selling XX = 20 gemstones, the remaining gemstones are 148 20 = 128. In Roman numerals, 128 is written as CXXVIII.
Calculate the difference between CXXVIII and LXXII.
The difference between CXXVIII and LXXII is LVI.
The numbers are CXXVIII = 128 and LXXII = 72. Subtracting them gives 128 72 = 56. The Roman numeral for 56 is LVI.
A museum is cataloging artifacts and finds that the combined weight of two artifacts is CXXVIII kilograms. If one artifact weighs XLV kilograms, what is the weight of the second artifact?
The weight of the second artifact is LXXXIII kilograms.
The total weight is CXXVIII = 128 kilograms, and one artifact weighs XLV = 45 kilograms. The weight of the other artifact is 128 45 = 83. The Roman numeral for 83 is LXXXIII.
Convert the sum of 100 and 28 into Roman numerals using the expansion method.
The Roman numeral for 100 + 28 is CXXVIII.
Step 1: Convert the numbers 100 and 28 into Roman numerals.
100 = C
28 = XXVIII
Add the numbers: 100 + 28 = 128.
Using the expansion method: 128 = 100 + 20 + 8 = CXXVIII.