A flonum represents a floating point number. The translation is indirect: a decimal floating point number from the text is converted by as to a generic binary floating point number of more than sufficient precision. This generic floating point number is converted to a particular computer's floating point format (or formats) by a portion of as specialized to that computer.

A flonum is written by writing (in order)

At least one of the integer part or the fractional part must be present. The floating point number has the usual base-10 value.

as does all processing using integers. Flonums are computed independently of any floating point hardware in the computer running as .