The Mathematica Book, Fifth Edition -

amazon.com/Mathematica-Book-Fifth-Stephen-Wolfram/dp/1579550223">bookstore or library near you, or The Mathematica Book, by Stephen Wolfram

Open a Mathematica notebook and type the examples directly from the book to see live results. The Mathematica Book, Fifth Edition

This section serves as a readable tutorial for basic operations. amazon

Begin with the "A Tour of Mathematica" section for a high-level overview of capabilities. or The Mathematica Book

Numerical and symbolic calculations, building basic functions, and an introduction to the notebook interface. Part 2: Principles of Mathematica

Includes a comprehensive Reference Guide and an index with over 10,000 entries.