This activity introduces children to Roman numerals. Comparing the number of numerals used in the two different systems makes an interesting context in which to practise interpreting and creating Roman numerals.
You could begin by inviting learners to share anything they know already about Roman numerals.
Challenge learners to decipher the Roman numerals given (perhaps in pairs) and use these examples to draw out the three rules. You could then invite pairs to create the Roman numerals for the numbers written in Arabic numerals in the problem, which will help them familiarise themselves with the rules.
The group can then work on the task of finding numbers which use fewer numerals in the Roman numeral system than the Arabic system.
How did you work this one out?
What would you say are the differences between Roman numerals and the ways we write numbers now?
Learners might enjoy investigating which Roman numerals read the same backwards as forwards.