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 more. 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. Have you ever noticed these symbols and wondered what they represent? Those are Roman numerals. In ancient times, people counted using fingers, sticks, bones, etc. As life became more complex, a standardized counting system was needed. Ancient Romans developed the Roman numeral system. The symbols I (1), V (5), X (10), L (50), C (100), D (500), and M (1000) are used to count.
In Roman numerals, we use DCCXCI to represent 791, where D is 500, CC is 200, XC is 90, and I is 1. Let’s learn more about Roman numerals and how we write them.
There are certain basic rules to write numbers in Roman numerals. In this section, let’s discuss some basic rules that need to be remembered when writing numbers in Roman numerals.
The addition method is used when smaller numbers are placed after larger numbers. For example, VI → V + I → 5 + 1 = 6.
Certain Roman numerals can be repeated up to three times to form larger numbers. For example, CCC → 300.
If a smaller number precedes a larger number, it is subtracted from the larger number. 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.
Let’s now learn how to write 791 in Roman numerals. Follow these methods to write the number in Roman numerals.
In the expansion method, the number is broken down based on place value. In this section, we will learn how to write 791 in Roman numerals using the expansion method.
To write 791 in Roman numerals, follow the steps:
Step 1: Break the number based on place value: hundreds, tens, and ones. For 791, we write it as 700 + 90 + 1.
Step 2: Convert each number into Roman numerals:
Step 3: Combine the Roman numerals: Therefore, 791 in Roman numerals is DCC (700) + XC (90) + I (1) = DCCXCI.
When writing large numbers in Roman numerals, we group the numbers. To write 791 in Roman numerals, we group 791 as 700 + 90 + 1:
So, 791 is written as DCCXCI 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 the ways to avoid them.
A historian found a scroll that was dated using Roman numerals as DCCXCI years ago. How many years ago was this in modern numerals?
The scroll was dated 791 years ago.
The Roman numeral DCCXCI is equivalent to 791 in modern numerals.
Therefore, the scroll was dated 791 years ago.
An architect designed a building with DCCXCI windows, to be equally divided among XXI floors. How many windows will each floor have?
Each floor will have XXXVII windows.
To find the number of windows per floor, divide the total number of windows by the number of floors: DCCXCI / XXI.
DCCXCI = 791
XXI = 21
791 / 21 = 37
37 in Roman numerals is XXXVII.
A collector has a rare coin collection with a total value of DCCXCI dollars. If the collector decides to sell part of the collection worth CCXLIV dollars, what is the remaining value of the collection?
The remaining value of the collection is DXLVII dollars.
Subtract the value of the part sold from the total collection value:
DCCXCI = 791
CCXLIV = 244
791 - 244 = 547
547 in Roman numerals is DXLVII.
A library has a total of DCCXCI ancient manuscripts. If they acquire an additional XLIX manuscripts, what will be the new total?
The new total of manuscripts will be DCCCXL.
Add the number of newly acquired manuscripts to the existing total:
DCCXCI = 791
XLIX = 49
791 + 49 = 840
840 in Roman numerals is DCCCXL.
Write the Roman Numeral for the difference between DCCLXXXI and IX using the expansion method.
The Roman numeral for the difference is DCCLXXII.
Step 1: First convert the numbers 781 and 9 into Roman numerals
781 - DCCLXXXI
9 - IX
Find the difference: 781 - 9 = 772
Using expansion method: 772 = 700 + 70 + 2 = DCCLXXII
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.