the difference between the usage of IV and IIII in roman numerals

In Roman numerals, each letter has a specific value that represents a number:

• I = 1
• V = 5
• X = 10
• L = 50
• C = 100
• D = 500
• M = 1000

When constructing Roman numerals, you generally combine the symbols in descending order to represent numbers. However, there is an exception in the way certain numbers are represented using subtraction, which is where the difference between "IV" and "IIII" becomes apparent.

Here's the breakdown:

• IV: This represents the number 4. In Roman numerals, when you want to represent a number that is one less than a multiple of 10, you place the numeral for 1 (I) before the numeral for 5 (V). So, IV is read as "one before five," which equals 4.

• IIII: If you were to write four 1s together (IIII), it would represent the number 4. This is straightforward addition: 1 + 1 + 1 + 1 equals 4.

The reason that you don't see "IIII" used in the context of standard Roman numeral representation is due to the efficiency of the system. The Romans used the principle of subtractive notation (where placing a smaller numeral before a larger numeral means subtracting the smaller from the larger) to avoid having to use too many symbols. So, instead of writing "IIII" for 4, they wrote "IV" to simplify the notation.

In summary, while "IIII" could technically be used to represent the number 4, "IV" is the conventional Roman numeral representation, combining simplicity and efficiency.