• 3-minute read
• 10th October 2018

How and When to Use Roman Numerals

What did the Romans ever do for us? Well, among other things, they gave us a way of writing numbers. These are known as Roman numerals, and chances are you’ve seen them used even if you’re not sure how they work.

Join us, then, for a quick look at how to use Roman numerals correctly.

How to Use Roman Numerals

When we think of numbers, we usually think of Hindu–Arabic numerals. These are the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. The Romans, however, used letters to represent numbers:

These symbols can be combined to create new numbers. This partly works by adding numerals until you reach the required value. For instance:

• V (5) + I (1) = VI (6)
• L (50) + X (10) = LX (60)
• M (1000) + L (50) + X (10) + V (5) + I (1) = (1066)

However, if a number requires using the same symbol four times in a row, you subtract from the next highest value instead. We indicate this by placing the smaller numeral in front of the larger one.

• I before V or X subtracts 1 (e.g., IV = 4)
• X before L or C subtracts 10 (e.g., XL = 40)
• C before D or M subtracts 100 (e.g., CM = 900)

This system works for numbers up to 3,999. However, you can also modify the numerals above for larger values. This involves placing a line over them to show that you’re dealing with thousands. As such, 4,000 would be written as “IV” with a line above the numerals. You can see some examples below.

When to Use Roman Numerals

Roman numerals are rare these days, but they are still used for:

• Chapter/section numbers in books and plays
• Page numbers for introductory material in a book
• Numbering items in a list
• Indicating the year of production for movies and TV shows
• Titles of film or game sequels
• Editions of long-running sporting events
• The titles of monarchs
• Numbers on some clocks and watches

This isn’t a complete list, but it does cover some places you’re likely to see Roman numerals in everyday life.

If you’d like any help checking that you’ve used numerals correctly in your writing, get in touch for all your proofreading needs!

Summary: How Do Roman Numerals Work?

Roman numerals use letters to represent numbers. In addition:

• The basic numerals can be combined to create new values.
• This involves adding numerals (e.g., “V” is 5 and “I” is 1, so “VI” is 6).
• However, if a number requires using the same numeral four times in a row, subtract from the next highest value instead (e.g., “IV” is 4).
• Typically, Roman numerals are only used for introductory pages or chapter numbers in a book; however, they’re also used for things like years of production in television and titles of movie sequels.