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Last updated on February 28th, 2025
To meet their daily commerce and administration needs, the ancient Romans developed Roman Numerals. They 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 CMI.
The ancient Romans discovered that counting fingers could get very complicated after 10. To overcome this complexity, the Roman numeric system was developed. This system 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. CMI in Roman numerals can be written in number form by adding and subtracting the values of each Roman numeral, i.e. CMI = 901.
Let us learn more about the Roman numeral CMI, how we write them, 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 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 larger symbol follows a smaller 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 CMI 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 involves breaking down Roman numerals into numerical form and adding or subtracting 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 or subtract the numerals accordingly.
For CMI,
Step 1: First, we break the Roman numerals. CMI = C + M - I
Step 2: Write the Roman Numerals for each part The Roman Numeral C is 100 The Roman Numeral M is 1000 The Roman Numeral I is 1
Step 3: Combine all the numbers C + M - I = 1000 + 100 - 1 = 901. Therefore, the Roman Numeral CMI is 901.
Using subtraction and addition rules, we apply the grouping method. This means we break the Roman numerals into smaller groups, making 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 CMI.
Step 1: The larger Roman numerals are what we will begin with. Once split, the Roman numerals we get are C, M, and I. The numeral for C is 100, and M is 1000.
Step 2: Now we need to either add or subtract the smaller number, depending on its place.
Here we subtract I from M and add C. Therefore, the numeral of CMI is 901.
Students can make mistakes when studying Roman numerals. Here are a few common mistakes students make, and ways to avoid them.
Combine CMI and XLII and express the result in Roman numerals.
The sum is CMXLIII
Convert both Roman numerals into their decimal form:
CMI = 901
XLII = 42
Add the numbers: 901 + 42 = 943
Convert the result back into Roman numerals: 943 = 900 (CM) + 40 (XL) + 3 (III) = CMXLIII
Subtract LXXV from CMI. Write the answer in Roman numerals.
The difference is DCCCXXVI
Convert the Roman numerals into their decimal form:
CMI = 901
LXXV = 75
ubtract the numbers: 901 - 75 = 826
Convert the result into Roman numerals: 826 = 800 (DCCC) + 20 (XX) + 6 (VI) = DCCCXXVI
Divide CMI by 3 and express the answer in Roman numerals.
CCCIII
Convert CMI into its decimal form:
CMI = 901
Divide by 3: 901 / 3 = 300 with a remainder of 1
Convert 300 into Roman numerals: 300 = CCC
The remainder can be expressed as I, resulting in CCCIII
Calculate the product of CMI and II.
MDCCCII
Convert CMI and II into their decimal forms:
CMI = 901
II = 2
Multiply the numbers: 901 × 2 = 1802
Convert 1802 into Roman numerals: 1800 (MDCCC) + 2 (II) = MDCCCII
Express CMI in its decimal form.
In decimal form, CMI is 901
Break CMI into components:
CM = 900
I = 1
Add the values: 900 + 1 = 901
Limitation Rule: There are some symbols that cannot be repeated more than once (V, L, D). For example, VV for 10 is wrong, the correct answer is X.
Place value: The position of a digit in a number; this position determines its value. For example, the number 9 in 901 is in the hundreds place.
Subtraction Method: The subtraction method is applied when a smaller numeral precedes a larger numeral. For example, IV for 4.
Roman Numerals: The ancient numeric system using combinations of letters from the Latin alphabet (I, V, X, L, C, D, M) to signify values.
Grouping Method: A way to break down Roman numerals into smaller parts for easier addition or subtraction to find their total value.
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.