This book is an introduction to combinatorial mathematics, also known as combinatorics. The book focuses especially, but not exclusively on the part of combinatorics that mathematicians refer to as “counting.” The book consists almost entirely of problems. Some of the problems are designed to lead you to think about a concept, others are designed to help you figure out a concept and state a theorem about it, while still others ask you to prove the theorem. Other problems give you a chance to use a theorem you have proved.
Thumbnail: Rubik's Cube. Image used with permission (CC BY-SA 3.0 Unported; Booyabazooka).