In researching old transcriptions from the Parish Register of Gargrave in Yorkshire, I stumbled upon a peculiar use of the letter “j” at the end of Roman numerals which seemed to alter the numbers’ usual endings. Initially thought to be a unique style quirk, I soon realized it was a common practice in Yorkshire before 1700. This puzzling phenomenon raises questions about its origins, significance, and widespread use. Surprisingly, the letter “j” was originally used as a flourish in Roman numerals and later evolved into a separate character to clarify the end of a number. This curious practice was even recommended in medical prescriptions until recently.
https://genealogy.stackexchange.com/questions/3748/what-is-the-significance-of-the-character-j-at-the-end-of-a-roman-numeral