A simple answer for your simple spreadsheet !
It sounds like you have something like this :
If you are going to add more data in cells G2 to G8 and want to perform the same calculation ( SUM ) as you did in Column F, then just Copy and Paste the sum across ( Right click in cell F9 and click Copy, then Right Click in the new cell - G9 and click Paste ) :
and Excel will automatically change the SUM to perform the same calculation on the data in your new Column :
Job done
