Roman Numerals

Thank you to everybody who submitted a solution to this activity.

Erica, Sarah and Annie in Wenona, Australia sent in solutions to the first part of this activity:

These are the answers we got for Roman Numerals:
III = 3
IV = 4
XVIII = 18
XIX = 19
MCMLXXVI = 1976
MMXXIII = 2023
MCMLXII = 1962

55 = LV
86 = LXXXVI
2592 = MMDXCII
913 = CMXIII
1984 = MCMLXXXIV

We received similar solutions from Amy at Luckwell Primary School, Julia at BIS in South Korea, Stanley at Smithy Bridge, Alfie in the UK and Thomas at St Mary's Academy in the UK - thank you all for sending in your solutions.

Thomas also suggested that X, L, C, D and M would be examples of numbers where the number of Roman numerals is fewer than the number of Arabic numerals for the same number. Are these the only examples where the number is represented by just one Roman numeral?

Albert from St Matthew's Primary in the UK added a suggestion to this list:

In our number system 2000 has four digits but in Roman numerals it only has 2 digits MM

EH and FH from Shebbear Primary School in England sent in some more suggestions:

CM MC DL LD ML LM

These are good ideas, although there are some extra rules for writing numbers as Roman numerals which mean that LD and LM are not allowed - we would actually write those as CDL and CML.

Andrew at BIS in Vietnam said:

Can you find some examples when the number of Roman numerals is fewer than the number of Arabic numerals for the same number?
My ideas :
1200 = MCC
1510 = MDX
2500 = MMD etc

It looks like there might be a lot of possibilities! I wonder what Andrew means by 'etc'?