This section begins with a discussion of the Number class in the java.lang package, its subclasses, and the situations where you would use instantiations of these classes rather than the primitive number types.

This section also presents the PrintStream and DecimalFormat classes, which provide methods for writing formatted numerical output.

Finally, the Math class in java.lang is discussed. It contains mathematical functions to complement the operators built into the language. This class has methods for the trigonometric functions, exponential functions, and so forth.