ctrl-r reg, where “ is the unnamed register from the last yank or delete.
If you have done a block selection and you want to paste, normally you would have to leave selection mode to this and there fore not be able to edit multiple lines at once.
say you have (below) and what to prepend ‘number’.
number one two three
Place cursor on ‘number’,
yiw to yank inner word. Move to ‘o’ of one.
ctrl-v to enter block selection,
jj to select ott vertically. Then I to enter insert mode.
ctrl-r " . ESC.
number number.one number.two number.three