(1) For the protocol that adds NFTs to Bitcoin, see Bitcoin Ordinals. (2) A number that identifies the sequence of an item; for example, "record #34 is invalid." Contrast with "cardinal number," which ...
The following is an excerpt from Beyond Infinity: An Expedition to the Outer Limits of Mathematics, by Eugenia Cheng Mathematics can be thought of as many things: a language, a tool, a game. It might ...