Hi, just trying to jump-start my ailing memory. Lewis Carroll built in some kind of simple arithmetical 'word test' into the first few words of the Alice book, whereby you count letters, starting in a random place and somehow end up always on the same word. Used to know it, just can't QUITE recall the details now... Can anyone else help please?

I think this is a universal method that can be used with many books.

You might be thinking of the Kruskal Principle.

I have seen it applied to Alice in Wonderland, and also many other books and documents.

In the May 1999 issue of GAMES Magazine, Martin Gardner published a trick using t......pendence. (Click on the highlighted text to try it yourself!)