Found in one of my books, The Arabian Nights, numbers stamped in invisible ink. I originally assumed they were some sort of quality mark, but I’ve checked my other books by that publisher and not a single one has the same markings so I am not sure anymore. The three numbers found are 5, 3 and 1. Each number is within a circle and most are on the right page stamped on or near the page number. The page number being center page at the bottom of each page.

I have a good feeling these have a boring and simple explanation, I still like to think there’s more to them. Makes the book more interesting in my opinion. Anyone have an explanation?