Although it is presented as a collection of lecture notes on numerical analysis, this is essentially a full-fledged online book on the topic. Written by a professor of mathematics at Pennsylvania State University, the 125-page document spans three chapters and covers various forms of differential and difference equations, methods for solving them, and linear algebra. Scattered throughout the text are example problems that illustrate important concepts. Each section is concluded with a set of exercises that build on the presented material. Unfortunately, solutions for these problems are not provided.