I am trying to add a formula in a series of cells that already have a cell
reference.
Example:
(current) =B4
(change to) =round(B4,3)

I have a long series of data that I want to preform a round function on but
do not want to have to do this one by one since there are so many.
Is it possible to add this formula without having to do this procedure one
cell at a time?