GNU Emacs Lisp Reference Manual

2.3.2: Floating Point Type

Emacs version 19 supports floating point numbers (though there is a compilation option to disable them). The precise range of floating point numbers is machine-specific.

The printed representation for floating point numbers requires either a decimal point (with at least one digit following), an exponent, or both. For example, 1500.0, 15e2, 15.0e2, 1.5e3, and .15e4 are five ways of writing a floating point number whose value is 1500. They are all equivalent.

See Numbers, for more information.