autoarg-mode is an interactive autoloaded compiled Lisp function in `autoarg.el'.

(autoarg-mode &optional ARG)

Toggle Autoarg mode, a global minor mode.
With a prefix argument ARG, enable Autoarg mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.

In Autoarg mode, digits are bound to `digit-argument', i.e. they
supply prefix arguments as C-DIGIT and M-DIGIT normally do.
Furthermore, C-DIGIT inserts DIGIT.
SPC terminates the prefix sequence and inserts
the digits of the autoarg sequence into the buffer.
Without a numeric prefix arg, the normal binding of SPC
is invoked, i.e. what it would be with Autoarg mode off.

For example:
`6 9 SPC' inserts `69' into the buffer, as does `C-6 C-9'.
`6 9 a' inserts 69 `a's into the buffer.
`6 9 SPC SPC' inserts `69' into the buffer and
then invokes the normal binding of SPC.
`C-u SPC' invokes the normal binding of SPC four times.

key binding
--- -------

SPC autoarg-terminate
0 .. 9 digit-argument
C-0 .. C-9 self-insert-command