How to Use Roman Numerals

It’s been hundreds of years since we stopped using Roman numerals in favour of the numbers we use today, but the Roman system of using different letters to represent specific values is far from extinct.

Since 2014, Roman numerals have been part of the national maths curriculum and taught in schools across the country. It may seem like an unusual thing to teach primary school pupils when modern usages are few and far between, but learning about Roman numerals can help reinforce other important maths skills and improve children's understanding of how numbers work.

If you need a recap on Roman numerals before you head off to the classroom or before you get stuck in with the homework, we’ve got you covered.
 

What are Roman numerals?

Roman numerals are a set of letters that are used to represent a specific value. These are the letters traditionally used and the numbers they represent:

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

If you want to represent a number between any of these standard letters, you usually do this by combining letters to add up to the number you want.
 

How do you use Roman numerals?

There are three main rules to follow when using Roman numerals:

1. Letters are written in value order, with letters representing larger numbers appearing first.
   For example:

2. If you put a smaller value before a larger one, you subtract it instead of adding it on.
   For example:

You should only subtract one value at a time. So, while you can use I and X to make IX (9), X and C to make XC (90) and C and M to make CM (900), you shouldn’t write IIX to show ‘8’ — it’s VIII.

3. The “proper” way to write a Roman numeral is to use as few letters as possible (unless you’d be breaking rule number two).  
   For example, you would write:

LX rather than XXXXXX (60)
IX rather than VIIII (9).
 

Weirdly there’s no Roman numeral for the number zero. This is because the Romans only used this numeral system for counting objects they knew existed.

By the way, if you’re interested, the handy video below is great for explaining Roman numerals to children:

 

When do primary school children learn about Roman numerals?

Children first come across Roman numerals in Year 3 when learning how to tell the time. This is a nice, gentle introduction to the numerals for 1-12 as there’s no real difference between reading the time from a normal clock versus one with Roman numerals (except the obvious). The position of the hands will still give the same time and children should come to relate the numbers they’re used to seeing on a clock with the Roman numerals.

This Telling the Time PowerPoint for Year 3 features slides on reading clocks with Roman numerals and children can practise using clocks with Roman numerals with this worksheet.

In Year 4, children will be taught the numerals for 1-100 (that’s I-C in Roman numerals). They’ll also learn how our use of numbers has changed over time to include ideas like ‘place value’ and ‘having a number for zero’.

Check out this video for introducing the Roman numerals — it’s perfect for Year 4 children. There’s also this fun Crack the Code worksheet on Roman numerals — it comes in a foundation and stretch version too.

Children are taught the numerals all the way up to 1000 (M) in Year 5. They also learn to recognise years written in Roman numerals (having M in their arsenal is very useful for this!).

You could try these Year 5 worksheets for practising converting Roman numerals and coming up with a mnemonic memory aid for remembering the order of the Roman numerals.
 

How to help children with Roman numerals

Here are a few ways you can help children practise Roman numerals in and outside of the classroom:

• Encourage them to look out for Roman numerals and work them out wherever they can. This might be on clock faces, in the titles of films or books or the year of production at the end of a TV show’s credits.
• Involve numbers when learning about other parts of Roman history. Can they design a Roman shield that includes their lucky number as a Roman numeral?
• Ask them to use Roman numerals in other areas of maths. Can they work out a calculation made up of Roman numerals?
• Try some of our interactive games. Our Outback Clocks and Goose on the Loose Clocks games both feature a level on reading the time from clocks with Roman numerals. Our Ordering Numbers Arcade and Ordering Numbers Lab games both have Roman numeral levels for Years 4 and 5.

 

That’s it for our “Roman numerals CI”…

Through learning about Roman numerals, children will see how numbers can be represented in different ways. They’ll also realise that numbers weren’t always the same as they are today. Hopefully they’ll agree that our modern numbers are a lot easier to use!