CMXX Roman Numerals: Rules, Solved Examples & Practice Questions

CMXX Roman numeral represent the number 920 in the Roman numeral system. This numeral is formed by combining 900 (CM) and 20 (XX). Where the subtraction rule is applied, placing a smaller numeral before a larger one indicates subtraction, while adding smaller numerals after larger ones adds their value. Understanding how to read and write CMXX helps students grasp the logic of Roman numerals, improve number recognition, and see how historical number systems are still used today in clocks, book chapters, movie titles, and dates. Learning CMXX also strengthens logical thinking and makes working with Roman numerals easier and more meaningful.

Table of Contents

• How to Write CMXX Roman Numeral in Numbers?
• Numbers Related to CMXX Roman Numerals
• Basic Rules for Writing Roman Numerals
• Solved Examples on CMXX Roman Numeral
• Practice Questions on CMXX Roman Numeral
• Conclusion
  
  

How to Write CMXX Roman Numeral in Numbers?

To convert CMXX Roman numerals into numbers, we need to understand the value of each Roman numeral symbol and then add or subtract them according to Roman numeral rules.

Let us break the Roman numeral CMXX into individual symbols:

CMXX = (M - C) + X + X = CM + XX

Now replace each symbol with its numerical value:

• C = 100

• M = 1000

• X = 10

• X = 10

Next, apply the subtraction rule where a smaller number comes before a larger number (C before M).

CM = 1000 − 100 = 900

Then add the remaining values:

CMXX = (1000 - 100) + 10 + 10 = 900 + 20 = 920

Therefore, the number represented by CMXX in Roman numerals is 920.

Numbers Related to CMXX Roman Numerals

Basic Rules for Writing Roman Numerals

1. Know the symbols: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000.

2. Subtraction rule: A smaller numeral before a larger one means subtract.

Example: CM = 1000 − 100 = 900

3. Addition rule: A smaller or equal numeral after a larger one means add.

Example: XX = 10 + 10 = 20

4. Combine values: CM + XX = 900 + 20 = 920

So, CMXX = 920. Simple, clear, and easy to follow.

Solved Examples on CMXX Roman Numeral

Example 1: Find the sum of CMXX and LXXXV.

Solution:

First, convert the Roman numerals into numbers.

• CMXX = 900 + 20 = 920

• LXXXV = 80 + 5 = 85

Now add the numbers:

• 920 + 85 = 1005

Convert 1005 into Roman numerals:

1005 = 1000 + 5

= M + V

= MV

Therefore, CMXX + LXXXV = MV.

Example 2: A library recorded CMXX books last year and CL books this year. Find the total number of books in Roman numerals.

Solution:

Convert the Roman numerals into numbers.

• CMXX = 920

• CL = 150

Now add them:

• 920 + 150 = 1070

Convert 1070 into Roman numerals:

1070 = 1000 + 70

= M + LXX

= MLXX

Therefore, the total number of books is MLXX.

Example 3: Find the Difference Between CMXX and CCXL.

Solution:

Convert the Roman numerals into numbers.

• CMXX = 920

• CCXL = 240

Now subtract:

• 920 − 240 = 680

Convert 680 into Roman numerals:

680 = 500 + 100 + 80

= D + C + LXXX

= DCLXXX

Therefore, CMXX − CCXL = DCLXXX.

Example 4: Find the Product of CMXX and II.

Solution:

First, convert CMXX into numbers.

• CMXX = 920

• II = 2

Now multiply:

• 920 × 2 = 1840

Convert 1840 into Roman numerals:

1840 = 1000 + 800 + 40

= M + DCCC + XL

= MDCCCXL

Therefore, CMXX × II = MDCCCXL.

Example 5: A company produced CMXX units in a month. If the total production is divided equally into XL groups, find the number of units in each group. Write the answer in Roman numerals.

Solution:

Convert the Roman numerals into numbers.

• CMXX = 920

• XL = 40

Now divide:

920 ÷ 40 = 23

Convert 23 into Roman numerals:

23 = 20 + 3

= XX + III

= XXIII

Therefore, each group will have XXIII units.

Practice Questions on CMXX Roman Numeral

1. Write the Roman numeral CMXX in standard number form. What number does it represent?
2. Convert the number 920 into Roman numerals and explain how the symbols combine to form CMXX.
3. Add CMXX and LXXX. Write the final answer in Roman numerals.
4. Subtract CC from CMXX. What is the result in Roman numerals?
5. A school collected CMXX notebooks for donation and later added LX more. Find the total number of notebooks in Roman numerals.
6. What is the value of CMXX + X? Write the answer in Roman numerals.
7. Subtract XX from CMXX and express the result in Roman numerals.
8. What number comes just after CMXX? Write it in Roman numerals.
9. Find the difference between CMXX and D. Write the answer in Roman numerals.
10. Divide CMXX by X. Write the quotient in Hindu-Arabic numerals.
    
    

Conclusion

CMXX Roman numerals represent the number 920 in the Roman numeral system. It is formed by combining CM (900) and XX (20) using the standard Roman numeral rules. Understanding how CMXX Roman numerals are written helps students learn how larger numbers are created using both addition and subtraction principles. Practising numbers like 920 in Roman numerals improves number recognition skills and makes it easier for learners to read and write Roman numerals correctly in mathematics and everyday contexts.

Understand CMXX Roman numerals with simple explanations and step-by-step learning at Orchids International School.