At the right side of the main window are buttons labeled like so:
These are special commands called Popups because a new window 'pops up' from which you can choose a letter/digit/word.?? Suf $!% 1-9 Cmd
'Suf' is for suffixes like ED, ING, LY, and TION.
'$!%' is for punctuation characters. All special characters appear here.
'1-9' is where digits and arithmetic operators are chosen. You can choose many in a row keeping the popup up. Choose 'Done' when you are finished.
'Cmd' is for accessing a variety of other commands such as Quit, MailMe, Color, Abbr, AddW, TopW, Define, Synonym, Environ, TV, Bounce, Match, Sudoku, and UnScram.
In all of these popups there is a way to cancel it by choosing a blank area (or Done).