This is in contrast with how pi is otherwise consistently expressed on the Disc, which is "three and a bit."

Notably, Bloody Stupid Johnson is so skilled/inept that he actually does make pi equal to three within the machine... somehow... which breaks reality in a small amount of space inside it.

Apparently King David had this skill as well, since this is mentioned twice in the old testament:

1 Kings 7:23: And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it round about.