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Last updated on February 26th, 2025

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LXX Roman Numerals

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Foundation
Intermediate
Advance Topics

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 LXX.

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What is LXX in Roman Numerals?

Ancient Romans discovered that counting fingers could get very complicated after 10. So, to overcome this 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. LXX in Roman numerals can be written in number form by adding the values of each Roman numeral, i.e., LXX = 70.

 

Let us learn more about the Roman numeral LXX, how we write it, the mistakes we usually make, and ways to avoid these mistakes.lxx roman numerals

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Basic Rules for LXX 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 smaller symbol precedes a larger 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.

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How to Write LXX in Roman Numerals?

Let us learn about how to write LXX in Roman numerals. There are two methods that we can use to write Roman numerals:

 

  • By Expansion Method
  • By Grouping Method
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LXX 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 LXX,

 

Step 1: First, we break the Roman numerals. LXX = L + X + X

 

Step 2: Write the Roman numerals for each part The Roman numeral L is 50 The Roman numeral X is 10

 

Step 3: Combine all the numbers L + X + X = 50 + 10 + 10 = 70. Therefore, the Roman numeral LXX is 70.

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LXX 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 LXX.

 

Step 1: The larger Roman numerals are what we will begin with. Once split, the Roman numerals we get are L and XX. The numeral for L is 50

 

Step 2: Now we need to add the smaller number. Here we add XX to L, and we will get LXX. The Roman numeral XX is 20 Therefore, the numeral of LXX is 70.

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Common Mistakes and How to Avoid Them in LXX 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

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Mistakes when applying the repetition method

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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.

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LXX Roman Numerals Examples

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Problem 1

Convert the year LXX into the current Gregorian calendar year and calculate how many years ago that was from 2023.

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The year LXX corresponds to 70 AD. From 2023, that was 1953 years ago.

Explanation

Convert LXX into decimal form:

LXX = 70

Calculate the difference from 2023: 2023 - 70 = 1953

Hence, 70 AD was 1953 years ago from 2023.

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Problem 2

A historical artifact was dated to LXXII years after a major event. If the event occurred in 1 AD, what is the year of the artifact in Roman numerals?

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The year of the artifact is LXXIII.

Explanation

The event occurred in 1 AD.

LXXII = 72

1 AD + 72 years = 73 AD

Convert 73 into Roman numerals: 73 = 70 (LXX) + 3 (III) = LXXIII

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Problem 3

A manuscript contains LXX pages. If a scholar reads 10 pages per day, how many days will it take to complete the manuscript?

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It will take 7 days to complete the manuscript.

Explanation

Convert LXX into decimal form:

LXX = 70

Divide the total pages by the reading rate: 70 pages ÷ 10 pages/day = 7 days

Thus, it will take 7 days to read the manuscript.

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Problem 4

A historian found that a Roman soldier marched LXX miles in a week. Calculate the average distance in miles the soldier marched per day.

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The soldier marched an average of X miles per day.

Explanation

Convert LXX into decimal form:

LXX = 70

Divide the total miles by the number of days in a week: 70 miles ÷ 7 days = 10 miles/day

Convert 10 into Roman numerals: 10 = X So, the soldier marched an average of X miles per day.

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Problem 5

Convert the Roman numeral LXX into its decimal form.

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In decimal form, LXX is 70.

Explanation

Break LXX into components:

L = 50

XX = 20 (X + X)

Add values: 50 + 20 = 70

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FAQs on LXX in Roman Numerals

1.What is LX in Roman numerals?

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2.Is LXX a prime number?

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3.What is LXX + LXX?

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4.What is LXXX?

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5.Subtract X from LXX

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Important Glossaries for LXX in Roman Numerals

  • Addition Method: A method where larger symbols are followed by smaller symbols, and their values are added.
     
  • Repetition Method: A technique where symbols are repeated to increase their value, but not more than three times.
     
  • Subtraction Method: A method used when a smaller numeral precedes a larger numeral, indicating subtraction.
     
  • Numeral Grouping: A technique of breaking down numerals into parts to simplify calculation.
     
  • Place Value: The numerical value that a digit has by virtue of its position in a number.
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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.

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Fun Fact

: She loves to read number jokes and games.

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