Why were Ionic Greek numerals difficult for many traders to use?

Ionic Greek numerals, also known as alphabetical numerals, were a cipher system that assigned specific Greek letters to represent numbers 1–9, 10–90, and 100–900. While this system was well-suited for the theory of numbers, it was more difficult for the trading classes to comprehend compared to other systems.1

The primary difficulty for traders stemmed from the nature of the system itself: it required the user to memorize a large number of different symbols to represent various values. Unlike simpler grouping systems where a small set of symbols could be easily recognized and manipulated, the Ionic system necessitated that the operator be able to automatically recall the specific numerical meaning assigned to each letter. Consequently, while the system allowed for a compact notation, it lacked the intuitive simplicity that made other systems more accessible for the practical, everyday arithmetic required in commerce.1