Many were under one page. Most proofs pulled ideas from several areas of mathematics, and it seems to be this wonderful mixing of diverse ideas that leads to many of these proofs being in this book. Some of the proofs are recent, some date back to Euclid and others are noted as folklore proofs. Each section has several chapters, each about one central theorem or group of similar theorems. Most chapters are under ten pages long.
Some chapters present several different proofs of one theorem.
Other chapters presents several related theorems. There is also very readable exposition in each chapter that gives some of the history of the different proofs presented, some background and definitions along with examples in the margins, and sometimes some open questions related to the theorems and proofs presented. A few chapters have appendices which give more background for those unfamiliar with the basic concepts. Each chapter also gives references and is thus somewhat self contained. I found it interesting to note that many of the proofs used either induction, sometimes in a non-standard way, or were proofs by contradiction.