This book introduces Java programmers to numerical computing. It contains clear, non-theoretical explanations of practical numerical algorithms, including safely summing numbers, finding roots of equations, interpolation and approximation, numerical integration and differentiation, and matrix operations, including solving sets of simultaneous equations. Many of the programs are applets that take advantage of Java's interactive graphics capabilities. These programs allow the user to interact with them as they dynamically demonstrate the computational algorithms in action. Java Number Cruncher devotes several chapters to searching for patterns in the prime numbers, generating random numbers, intriguing formulas for pi and e, arbitrarily long numbers and their relationship to data encryption, and algorithms for creating fractal images. Working Java programs demonstrate all the concepts from this book.