When using Roman (upper and lower) numbers, the highest number that the user will see as a Roman number is 3999. I believe that this is because the number 4000 in Roman numbers includes re-equipment. If you are looking for information about [Exploring Roman Numerals](https://www.europeanbusinessreview.com/beyond-xxv-and-xxviii-exploring-other-roman-numerals-2/), here is the link, there is an interesting article.