(A) If one column has already been filled down to a certain number of rows, then adjacent columns can be filled down to the same height by this prodecure:
Highlight the first row in the columns you want to fill down.
Double click the lower right corner of the highlight box.
(B)To fill down a column for the first time (with no other filled columns available):
-Enter formula in first cell
-Select the first cell again
-Type Ctrl+C to copy (dotted line appears around cell)
-Click in address box and type in the range (e.g. A1:A1500) followed by Enter. This will select the range to be filled
-Type Ctrl+V to paste formula into all selected cells
-Type 'Esc' to edit copypaste mode