[zozbot234]

In ancient times, "reading silently" was considered a special skill that very few people had. Most literate people back then would read by sounding words aloud.

[slavik81]

How did they read Roman numerals? Unlike most words, I would imagine those were pronounced quite differently from how they were written.

[tsimionescu]

They weren't sounding letters, they were sounding words. I imagine the same would be true for numerals. They wouldn't go "X I I K I D S", they would go "twelve kids".