125 LearnersLast updated on May 26th, 2025
MXXI in Roman Numerals
To meet their daily commerce and administration needs, the ancient Romans developed Roman Numerals. It used a combination of seven symbols — I, V, X, L, C, D, and M to represent numbers. Roman numerals were used to record transactions, keep track of data, and label military units. In this topic, we are going to learn about the Roman numeral MXXI.
What is MXXI in Roman Numerals?
Ancient Romans discovered that counting fingers could get very complicated after 10. So to overcome the complexity, the Roman numeric system was developed. This was widely used throughout Europe as a standard writing system until the late Middle Ages.
Seven symbols are used to represent numbers in the Roman numeric system — I, V, X, L, C, D, and M. The numerals are made up of different combinations of these symbols. MXXI in Roman numerals can be written in number form by adding the values of each Roman numeral, i.e. MXXI = 1021.
Let us learn more about the Roman numeral MXXI, how we write them, the mistakes we usually make, and ways to avoid these mistakes.
Basic Rules for MXXI in Roman Numerals
When writing Roman numerals, there are a few rules that we need to follow based on the Roman numerals we are trying to write. In this section, we will learn about the rules when writing Roman numerals and how to represent them.
Rule 1: Addition Method:
When a larger symbol is followed by a smaller symbol, we add the numerals to each other. For example, in VIII, we have 5 + 3 = 8
Rule 2: Repetition Method:
A symbol that is repeated three times in continuation increases the value of the numeral. For example, XXX = 30
Rule 3: Subtraction Method:
We use the subtraction method when a larger symbol follows a smaller symbol. For example, XL = 40 (which is 50 – 10).
Rule 4: Limitation Rule:
Symbols cannot be repeated more than three times, and some symbols, such as V, L, and D cannot be repeated more than once. For example, 10 is represented as X and not VV.
How to Write MXXI in Roman Numerals?
Let us learn about how to write MXXI in Roman numerals. There are two methods that we can use to write Roman numerals:
- By Expansion Method
- By Grouping Method
MXXI in Roman Numeral by Expansion Method
The breaking down of Roman numerals into parts and then converting them into numerals is what we call the expansion method. The expansion method is the breaking down of Roman numerals into numerical form and adding them to get the final number.
Step 1: Break the Roman numerals into parts.
Step 2: Now write each of the Roman numerals with its numerical digit in the place value.
Step 3: Add the numerals together.
For MXXI,
Step 1: First we break the Roman numerals. MXXI = M + X + X + I
Step 2: Write the Roman Numerals for each part The Roman Numeral M is 1000 The Roman Numeral X is 10 The Roman Numeral I is 1
Step 3: Combine all the numbers M + X + X + I = 1000 + 10 + 10 + 1 = 1021. Therefore, the Roman Numeral MXXI is 1021.
MXXI in Roman Numeral by Grouping Method
Using subtraction and addition rules, we will apply the grouping method. This means we break the Roman numerals into smaller groups, which makes it easier to work with. This method groups the Roman numerals logically, and then we write the numbers for each group.
Step 1: Take the largest number and write the number for that Roman numeral.
Step 2: Write the Roman numeral using the subtraction and addition rules.
Example: Let’s take the Roman numeral MXXI.
Step 1: The larger Roman numerals are what we will begin with. Once split, the Roman numerals we get are M, XX, and I. The numeral for M is 1000 The numeral for XX is 20
Step 2: Now we need to either add or subtract the smaller number, depending on its place. Here we add I to MXX and we will get MXXI. The Roman numeral I is 1 Therefore, the numeral of MXXI is 1021.
Numbers Related to MXXI in Roman Numerals
We follow a pattern when it comes to writing Roman numerals. In this section, we will write some numbers related to the Roman numeral MXXI:
| Roman Numeral | Number | Breakdown |
|---|---|---|
| M | 1000 | M |
| X | 10 | X |
| M + X | 1010 | M + X |
| XX | 20 | X + X |
| MXX | 1020 | M + XX |
| I | 1 | I |
| MXXI | 1021 | MXX + I |
Common Mistakes and How to Avoid Them in MXXI Roman Numerals
Students can make mistakes when studying Roman numerals. Here are a few common mistakes students make, and ways to avoid them.
Mistake 1
Mistakes when applying the repetition method
It can be quite confusing for beginners to remember that Roman Numerals cannot be repeated more than three times. Another thing to keep in mind is that Roman Numerals such as V, L, and D cannot be repeated.
For example, writing LL as 100 is incorrect, the correct answer is C.
MXXI in Roman Numerals Examples
Problem 1
Find the sum of MXXI + LXXX. Write the answer in Roman numerals.
The sum is MCIC
Explanation
Convert both Roman numerals into their decimal form:
MXXI = 1021
LXXX = 80
Now add both numbers: 1021 + 80 = 1101
Now convert the number into its Roman numeral: 1101 = 1000 (M) + 100 (C) + 1 (I) = MCIC
Problem 2
What is the difference between MXXI - DCCC? Write in Roman numerals.
The difference is CCXXI
Explanation
Convert the Roman numerals into their decimal form:
MXXI = 1021
DCCC = 800
Now subtract the numbers: 1021 - 800 = 221
Convert the number into its Roman numeral: 221 = 200 (CC) + 20 (XX) + 1 (I) = CCXXI
Problem 3
Divide MXXI by 5 and write the answer in Roman numerals.
CCIV
Explanation
Convert MXXI into its decimal form:
MXXI = 1021
Divide by 5: 1021 / 5 = 204
Write 204 in Roman numerals: 204 = 200 (CC) + 4 (IV) = CCIV
Problem 4
Find the product of MXXI and III.
MMMLXIII is the product of MXXI and III.
Explanation
Write MXXI and III in numbers:
MXXI = 1021
III = 3
Multiply the numbers: 1021 × 3 = 3063
Convert 3063 into its Roman numerals: 3000 (MMM) + 60 (LX) + 3 (III) = MMMLXIII
Problem 5
Convert MXXI into its decimal form.
In decimal form MXXI is 1021
Explanation
Break MXXI into components:
M = 1000
XX = 20 (X + X)
I = 1
Add values: 1000 + 20 + 1 = 1021
FAQs on MXXI in Roman Numerals
1.What is XXI in Roman numerals?
2.Is MXXI a prime number?
3.What is MXXI + MXXI?
4.What is XXXI?
5.Subtract XXI from MXXI
6.How can children in Singapore use numbers in everyday life to understand MXXI in Roman Numerals?
7.What are some fun ways kids in Singapore can practice MXXI in Roman Numerals with numbers?
8.What role do numbers and MXXI in Roman Numerals play in helping children in Singapore develop problem-solving skills?
9.How can families in Singapore create number-rich environments to improve MXXI in Roman Numerals skills?
Important Glossaries for MXXI in Roman Numerals
- Addition Method: A method where you add the values of symbols when a larger numeral precedes a smaller one. For example, VI = 5 + 1 = 6.
- Subtraction Method: A method used when a smaller numeral precedes a larger numeral, indicating subtraction. For example, IV = 5 - 1 = 4.
- Repetition Method: A method where a numeral repeated up to three times is added together. For example, III = 1 + 1 + 1 = 3.
- Limitation Rule: Certain symbols like V, L, and D cannot be repeated in succession.
- Grouping Method: A technique of breaking down numerals into smaller groups to simplify addition or subtraction, often using subtraction and addition rules.
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Hiralee Lalitkumar Makwana
About the Author
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.
Fun Fact
: She loves to read number jokes and games.
