Farsley Farfield Class 6S blog

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Jessica makes a marvellous mistake while deciphering Roman numerals


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Look at these two pictures. One is correct while the other one is not. Can you figure out which one Jess made a mistake on? Jess spotted her own error when she referred back to her rules for deciphering Roman numerals

When deciphering Roman numerals, a key rule is:

If the numeral to the left of another numeral is worth less, you subtract its value from the one on the right.

eg IX = 10 – 1 = 9

With longer numbers you must read each sequence of numerals carefully. In this way you can find the pairs of numerals which may need to go through some ‘subtractive notation’.


M (1000)   CM (1000 – 100 =900)  LXX (50 + 10 + 10 = 70) IV  (5 – 1 = 4)

The answer is 1974 – the year tha this blogger was born!

Well done Jess for making this marvellous mistake and showing us all the importance of finding pairs of numerals that require a little subtraction to get the correct answer.

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