How to copy one line n times?

Question

Google Sheets

I have a file with 80 thousand lines, I need to add a new column and specify the same value in each line in it. Just copying it down takes a lot of time, how can it be done in one or two steps?

Answer 1

Double-click on the autocomplete marker (the square in the lower right corner of the active cell) - and everything will "stretch" down by itself

Answer 2

You need to click on a column --> copy, then click on another column --> paste