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Roman Numerals

Maths: Year 3 & 4 National Curriculum, topic 5.1.8

Reading Roman Numerals

Roman numerals are the numbers used by people in Roman times.

Roman numerals

Roman numerals

  • In maths we tend to use 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 to write numbers.
  • The Romans used letters to show different numbers.
  • E.g. the number 2 is shown as two 1s (II).
  • E.g. the number 6 is shown as one 5 and one 1 (VI).
Rules of Roman numerals

Rules of Roman numerals

  • No single letter can be repeated more than 3 times.
  • If the digit to the right is a smaller number, you add it to the digit on the left:
  • VI →\rightarrow 5 and 1 →\rightarrow 5 + 1 = 6
  • If the digit to the left is a smaller number, you subtract it from the digit on the right:
  • IV →\rightarrow 1 and 5 →\rightarrow 5 − 1 = 4
Zero

Zero

  • The Romans did not have the idea of zero in their counting.
  • That means there is no zero in Roman numerals.
  • Roman numerals don't have place values like we use in maths.

Writing Roman Numerals up to 100

We can use our rules to write Roman numerals with amounts up to 100.

Multiples of 10.

Multiples of 10.

  • Certain multiples of 10 have special characters in Roman numerals.
  • E.g. the number 30 is written as three tens, XXX.
  • E.g. the number 55 is written as one fifty and one ten, LV.
Making up numbers

Making up numbers

  • To write a large number in Roman numerals, write the tens first and then the ones.
  • Then we add them together.
  • E.g. the number 76 is written as:
  • 70 is written as one five and two tens, LXX.
  • 6 is written as one five and one one, VI.
  • 76 is LXXVI in Roman numerals.
Rules

Rules

  • To make numbers up to 100, we need to add another rule.
  • A small letter to the left of a big letter has to be at least one-tenth of the big letter.
  • For example, for 99 we don't write IC.
  • I is equal to 1, which is less than one-tenth of 100 (10).
  • That means 99 is XCIX in Roman numerals.

Test yourself on Roman Numerals

  • What is 1 in Roman numerals?

  • What is 3 in Roman numerals?

  • What is the number represented by the Roman numeral 'IX'?

  • What is the number represented by the Roman numeral 'VIII'?

  • What is 80 in Roman numerals?

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