The title of this book is intended to be more of a challenge than a promise. No one can promise you that you will learn differential equations in 24 hours. That is up to you. What this book does is it makes it possible to learn basic differential equations in the minimum amount of time needed. It has a concise style of presentation and the right number of exercises and examples-not too many, not too few. All of the solutions to all of the exercises are presented in detail in Appendix 1. This allows reinforcement learning and verification of success. Biographical sketches of important mathematicians are included to provide additional motivation; however, they can be skipped in the interest of further time savings. The material which can be skipped appears in italics. The content taught here is equivalent to the material presented in the junior-level course in differential equations that the author teaches at University of Colorado Denver. It grew out of his earlier book, Shortcut to Ordinary Differential Equations. The present book, expanded slightly and equipped with all of the solutions, covers basically the same topics that were taught in a junior-level course in differential equations that the author took at Indiana University-Purdue University Indianapolis.