How to Write 21 in Roman Numerals?

Writing 21 in Roman numerals is straightforward once you understand the system. It is represented as XXI, where X stands for 10, another X adds another 10 to make 20, and I represents 1, bringing the total to 21. Roman numerals are formed by combining these symbols through simple addition, making them a fun and easy way to learn about ancient Roman numbering systems while enhancing math skills. Let us start the learning process by understanding different aspects of how to write 21 in Roman numerals.

How to Write 21 in Roman Numerals?

To write 21 in Roman numerals, you use the combination XXI. This is simply made by adding X (10) twice to make 20, and then adding I (1) to reach 21. There’s no need for any complex calculations or combinations – just the basics of Roman numerals!

Number	Roman Numeral
21	XXI

Roman Numerals 1 to 1000: Download Free PDF

How to Convert XXI to Number

To convert XXI from Roman numerals to a number, you need to know the values of the symbols and add them up. In XXI:

X = 10

X = 10

I = 1

Here, you add the two X’s (10 + 10) to make 20, and then add I (1) to get 21.

So, 20 + 1 = 21.

XXI = 21 So, if you see XXI alone, it directly represents the number 21

Exercise on 21 in Roman Numerals

Let us practice some questions on Roman Numerals here.

Addition and Subtraction

Add/subtract the following numbers and answer in Roman Numerals

1. 10 + 11 = ___
2. 30 – 9 = ___
3. 25 – 4 = ___
4. 50 – 29 = ___

Answers:

1. XXI
2. XXI
3. XXI
4. XXI

Convert to Roman Numerals

Convert the following numbers into Roman numerals:

1. 21
2. 27
3. 31
4. 41

Answers:

1. 21 = XXI 
2. 27 = XXVII
3. 31 = XXXI
4. 41 = XLI

Convert to Numbers

Convert the following Roman numerals to numbers:

1. LI
2. LXI
3. LXXI
4. LXXXI

Answers:

1. LI = 51
2. LXI = 61
3. LXXI = 71
4. LXXXI = 81

Match the Following

Match the following numbers to Roman numerals:

Numbers	Roman Numerals
(i) 21	(a) XII
(ii) 12	(b) XXXI
(iii) 31	(c ) XXI
(iv) 13	(d) XIII

Answers:

(i) 21 → (c) XXI

(ii) 12 → (a) XII

(iii) 31 → (b) XXXI

(iv) 13 → (d) XIII

Check out other Roman Numerals here:

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