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How to Read Roman Numerals – The Subtractive Principle

The ‘Subtractive Principle’ in Roman Numerals

Reading Roman Numerals

reading roman numerals

Reading Roman Numerals – Subtractive Principle

The technical term ‘subtractive principle’ simply means when smaller numerals are on the left of larger ones you subtract them to get the total.

IV = 1 before 5 = 4
IX = 1 before 10 = 9
XL = 10 before 50 = 40
XC = 10 before 100 = 90
CD = 100 before 500 = 400
CM = 100 before 1000 = 900

Personally I like the way it is shown on the graphic but you’ll have to work out which way works for you.

 

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