Google Sheets Tricks: Copy formula to whole column

I have learned this tricks in Google Sheets:

Drag and drop all the way down of a column can be a bit cumbersome.

To select all the cells below another one, you can use the hotkey Ctrl+Shift+Arrow Down.

Then you can for example copy/ paste on this whole selection.

To copy a formula in the whole row, you can edit the first cell and use an ArrayFormula

Example : 

=ARRAYFORMULA(IF(ISBLANK(E2:E);"";YEAR(E2:E)))

When you do so the cells must be empty else you will get an error that the formula would overwrite the existing value.