# What are Roman Numerals?

Roman numerals are a counting system that originated in ancient Rome. In Roman numerals, numbers are depicted using letters: I correspond to ‘1,’ and ‘IV’ means ‘4’. Although Arabic numerals are more common today, there are still many places where Roman numerals can be found.

What are Roman numerals?

Roman numerals are the numbers that the ancient Romans first used. They used combinations of letters from the alphabet (I, V, X, L, C, D, and M) to correspond to different numbers:

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

This numeral system continued to be used in ancient Rome and around Europe until the 14th century. However, from the 14th century, Roman numerals began to be replaced by the Arabic numerals that we use today (0, 1, 2, 3, 4, 5, 6, 7, 8, 9).

That being said, Roman numerals can still be found in many different places today. For example, clock faces tend to use Roman numerals. Also, we still use them when referring to kings and queens, such as Queen Elizabeth II.

As they’re commonly used in clock faces, most people are familiar with the Roman numerals up to 12.

Roman numerals chart

Roman numerals can be tricky to make sense of, so we’ve provided a handy chart that converts common numbers from Arabic into Roman numerals. This chart should be useful when introducing the topic to your learners!

 1 2 3 4 5 6 7 8 9 10 I II III IV V VI VII VIII IX X

 10 20 30 40 50 60 70 80 90 100 X XX XXX XL L LX LXX LXXX XC C

 100 200 300 400 500 600 700 800 900 1000 C CC CCC CD D DC DCC DCCC CM M

What are the rules for forming numbers with Roman numerals?

When we want to form numbers using Roman numerals, there are some essential rules that we need to follow. In this next bit, we’ll break down some of these rules so that you and your pupils can write with Roman numerals without making mistakes!

Adding the same symbols together adds to their value, so it’s the same rule as an addition: 1+1+1 = 3 or 10+10 = 20.

Example: I = 1, II = 2, III = 3, XX = 20

But remember, you can repeat the same symbol no more than three times. So, you write the number three as III, but you cannot write four as IIII – the correct way to write four is IV.

Using subtraction to form some numbers

No more than 3 identical letters ever appear consecutively. So, symbols are subtracted. Furthermore, the small number is subtracted if a smaller number is placed before a larger one.

Example: IV = 4 (5-1) and IX = 9 (10-1)

The subtraction rule is used in these six examples:

• I is placed before V and X: IV (4) and IX (9).
• X is placed before L (50) and C (100): XL (40) and XC (90).
• C is placed before D (500) and M (1000): CD (400) and CM (900).

The larger number appears first

You already know that adding different symbols makes other numbers. Roman numerals are often written in order from the biggest value number to the smallest. Remember, the larger number will appear first.

Example: VI = 6 VII = 7, XI = 11, XXI = 21, XXV = 25

How to convert Roman numeral dates

To write the date using Roman numerals, follow these simple steps:

1. Take the day of the month and write it in Roman numerals. Please keep it in lowercase.
2. Convert the month into a Roman abbreviation. Write it all in capitals. The Roman names for months are Januarius, Februarius, Martius, Aprilis, Maius, Junius, Julius, Augustus, September, October, November, and December. You’ll notice that these are very similar to the names of the months in English.
3. Convert the year into Roman numerals. Write it in all capitals.

Here are a few handy Roman numerals date examples:

27 September 1969 would be written as xxvii SEPT MCMLXIX.

1 June 1998 would be written as I JUN MCMXCVIII.

10 March 2006 would be written as x MART MMVI.

Your children could practice writing their birthdays in Roman numerals until they’ve got the hang of it!

How to Easily Remember the Vital Roman numerals

As we’ve learned, the letters used in Roman numerals are I, V, X, L, C, D, and M. But how can we remember them? Luckily, we’ve got a useful mnemonic to help you and your children:

I

Value

Xylophones

Like

Cows

Do