How Roman Numerals Work:

Roman Numerals can be tricky to understand – that’s why we’ve got a great roman numeral converter – but if you want to know how to convert the numbers yourself. Here is a guide...

The Basics... There are 7 numbers to learn:

Learn these 7 number units - Every Roman Numeral is made from a combination of these 7 numbers:

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

ADD the numbers up from Left to Right...

III = 1 + 1 + 1 = 3
VII = 5 (V) + 1 + 1 = 7

Simple so far!

A little bit trickier...

Always use as BIG number unit as possible to make the number you want:

Example:

• 6 would be V (for 5) and I (for 1). VI NOT IIIIII (1,1,1,1,1,1)
• 15 would be X (for 10) and (V for 5). XV NOT VVV (5,5,5)
• 156 would be C (for 100), L (for 50), V (for 5) and I (for 1). CLVI NOT LLLIIIIII (50,50,50,1,1,1,1,1,1)

So remember – use as BIG number as possible – not smaller ones! It helped save time writing!

The trickiest part!

This is where Roman numerals can get difficult – To make it even quicker to write numbers, the Romans decided to use 6 extra numbers, they are:

• IV = 4
• IX = 9
• XL = 40
• XC = 90
• CD = 400
• CM = 900

• So instead of writing IIII for 4 – Romans could now write IV.
• Instead of LXXXX for 90 – They could now write XC. A great time saver!

What these new numbers did was tell you to SUBTRACT the small number, if it is on the LEFT side of a big number.

• VI = 6 (With the I on the RIGHT of the V - Add)
• IV = 4 (With the I on the LEFT of the V - Subtract)

It's important to know though – that ONLY these 6 new combinations can be used together – so IX is a pair – meaning 9 – but you cannot have IL for 49. (It’s best just to learn the new 6 numbers!)

So how would you write 99?

To write 99 – you use XC for 90, then IX for the 9 – The answer: XCIX
Without the 6 new numbers - only the original 7, it would have been: LXXXXVIIII
(And just using Is would be: IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIIII IIIIIIIII)