If you have a formula that you want to copy down your table quickly, you can do it the slow way by dragging down the bottom right hand corner of the cell, or the quick way, which is to double click the bottom right hand corner of the cell.
As long as there is data to the left hand side of the formula you want to copy downwards, this trick will work.
STEP 1: Type in your Excel Formula
STEP 2: Double click on the lower right corner of the cell to apply the same formula to the rest of the column
The same Excel formula is applied to the entire column in a flash!