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Last updated on February 26th, 2025
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.
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.
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.
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.
A symbol that is repeated three times in continuation increases the value of the numeral. For example, XXX = 30.
We use the subtraction method when a smaller symbol precedes a larger symbol. For example, XL = 40 (which is 50 – 10).
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.
Let us learn about how to write LXX in Roman numerals. There are two methods that we can use to write Roman numerals:
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.
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.
Students can make mistakes when studying Roman numerals. Here are a few common mistakes students make, and ways to avoid them.
Convert the year LXX into the current Gregorian calendar year and calculate how many years ago that was from 2023.
The year LXX corresponds to 70 AD. From 2023, that was 1953 years ago.
Convert LXX into decimal form:
LXX = 70
Calculate the difference from 2023: 2023 - 70 = 1953
Hence, 70 AD was 1953 years ago from 2023.
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?
The year of the artifact is LXXIII.
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
A manuscript contains LXX pages. If a scholar reads 10 pages per day, how many days will it take to complete the manuscript?
It will take 7 days to complete the manuscript.
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.
A historian found that a Roman soldier marched LXX miles in a week. Calculate the average distance in miles the soldier marched per day.
The soldier marched an average of X miles per day.
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.
Convert the Roman numeral LXX into its decimal form.
In decimal form, LXX is 70.
Break LXX into components:
L = 50
XX = 20 (X + X)
Add values: 50 + 20 = 70
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.