digit-argument

digit-argument is an interactive compiled Lisp function in `simple.el'.

It is bound to C-9, C-8, C-7, C-6, C-5, C-4, C-3, C-2, C-1, C-0, ESC 0..9, C-M-9, C-M-8, C-M-7, C-M-6, C-M-5, C-M-4, C-M-3, C-M-2, C-M-1, C-M-0.

(digit-argument ARG)

Part of the numeric argument for the next command.
C-u following digits or minus sign ends the argument.