The old column in column a is the main query. This is an example I want the output to look like in column B.
Make a new column in column C. Looking for a formula to run all in one go.
Hope this makes sense.
To fill the blanks in the first column in situ (without creating another column):
Select column A using it's label at the top of the column
Press F5 on the keyboard
Click Special…
Double-click Blanks
(At this stage you have all the blank cells in column A selected, so keep them selected while:
you press the = symbol on the keyboard
then the up arrow on the keyboard
then hold the Ctrl key while you press the Enter key on the keyboard.
To make those formula results into plain values:
select the whole column A again
Copy (Ctrl+c if you want) Paste-Special:Values
Finished