GNU Emacs Manual - Arguments Go to the first , previous , next , last section, table of contents . Some commands interpret the argument as a repetition count. For example, C-f with an argument of ten moves forward ten characters instead of one. With these commands, no argument is equivalent to an argument of one.
Negative arguments tell most such commands to move or act in the opposite direction.
Digits and - modified with Control, or Control and Meta, also specify numeric arguments. C-u works on all terminals. To type a negative argument, type a minus sign after C-u . Just a minus sign without digits normally means -1. It multiplies the argument for the next command by four.