calculator-standard-displayer is a compiled Lisp function in `calculator.el'.

(calculator-standard-displayer NUM &optional CHAR GROUP-P)

Standard display function, used to display NUM.
Its behavior is determined by `calculator-number-digits' and the given
CHAR argument (both will be used to compose a format string). If the
char is "n" then this function will choose one between %f or %e, this
is a work around %g jumping to exponential notation too fast.

It will also split digit sequences into comma-separated groups
and/or remove redundant zeros.

The special `left' and `right' symbols will make it change the current
number of digits displayed (`calculator-number-digits').