How do you add line numbers to visually selected lines?
:'<,'>!nl -ba
Select lines visually, then run :'!nl -ba to pipe through the nl command which prepends line numbers to each selected line.
Tag: number
How do you switch to a buffer by its number?
:b3
Use :b followed by the buffer number.
How do you delete a specific buffer by its number?
:bd 3
Use :bd (bdelete) followed by the buffer number.
How do you use a macro to number each paragraph in a document?
qa{jI## Section \n<Esc>}q
Record a macro that goes to the start of each paragraph and inserts a section header.