Roman Numerals

Could a person who has not learned about Roman numerals work out which centurian does not get a shield?


Topics: Starter | Arithmetic

  • Steve, A Rather Puzzled Dad!!
  • This may be a somewhat bizarre question and for that I apologise in advance!

    I just wanted to say as a 'dad' your website is excellent and something my children and I enjoying learning on! Highly addictive and a brilliant learning tool.

    On learning Roman Numerals with my children on your website, they asked me a question, which I am unsure on the answer to! All was going well until they asked about their birthdays and how Romans wrote their birthdays....this is where I became unstuck.....

    I was trying to apply the logic from your website, so my daughters birthday is 20.12.2006, so in roman numerals that would be XX.XII.MMVI but on reading other articles on the web, there is mention of a roman calendar using three reference dates, Kalends, Nones and Ides.

    I fully appreciate that this is not your specialist area but I wondered whether you have ever been asked the question before?
  • Transum,
  • Dear Stephen,
    Thank you so much for the kind words about the Transum website.

    As you correctly assumed, Roman Numerals is not my specialist area but reading about the issue on and Wikipedia has provided the following information.

    Unlike the Julian and Gregorian calendars, the Roman calendar had a different system for numbering the days of the month. The months were divided into day markers that fell at the start of the month, the fifth or seventh day, and in the middle of the month. These 3 markers were called Calends, Nones and Ides.

    Calends (Kalendae, Kalends) signify the start of the new moon cycle and was always the first day of the month.

    Nones (Nonae) were known to be the days of the half moon which usually occur 8 days before the Ides.

    Ides occurred on the 15th day of March, May, July, and October, and the 13th day of the other months. They are thought to have been the days of the full moon.

    The day preceding the Kalends, Nones, or Ides was Pridie, e.g., Prid. Id. Mart. = 14 March. Other days were denoted by ordinal number, counting back from a named reference day. The reference day itself counted as the first, so that two days before was denoted the third day. Dates were written as a.d. NN, an abbreviation for ante diem NN, meaning "on the Nth (Numerus) day before the named reference day (Nomen)",21 e.g., a.d. III Kal. Nov. = on the third day before the November Kalends = 30 October. Further examples of date equivalence are: a.d. IV Non. Jan. = 2 January a.d. VI Non. Mai. = 2 May a.d. VIII Id. Apr. = 6 April a.d. VIII Id. Oct. = 8 October a.d. XVII Kal. Nov. = 16 October.

    So your daughter's birthday I think would be a.d. XIII Kal. Jan MMVI

    I hope that helps and that you continue to enjoy the Transum website.
  • Mr. Jennings, Twitter
  • Tina Berghella, Twitter
  • Friday, October 13, 2017
  • The Romans did not find algebra very challenging because X was always 10.

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Laptops In Lessons

Teacher, do your students have access to computers?
Do they have iPads or Laptops in Lessons?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here a concise URL for a version of this page without the comments.

Here is the URL which will take them to an interactive jigsaw puzzle of Roman numerals.

Student Activity


If you are not an expert on Roman numerals here is an explanation:


Numbers are formed by combining symbols together. So II is two ones, i.e. 2, and XIII is a ten and three ones, i.e. 13. There is no zero in this system, so 207, for example, is CCVII, using the symbols for two hundreds, a five and two ones. 1066 is MLXVI, one thousand, fifty and ten, a five and a one.

Symbols are placed from left to right in order of value, starting with the largest. However, in a few specific cases, to avoid four characters being repeated in succession (such as IIII or XXXX) these can be reduced using subtractive notation as follows:

Explanation adapted from the Wikepedia article on Roman numerals.




Clock 1 Clock 2 Clock 3

Which clockface is the odd one out?

The answer can be found by looking closely at the roman numerals used.



Extension Answer

Investigate which system of numbers is most common on clocks in your school, home or place of work.


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