Increase a row by 1 cell

[James]

Hello NG,
I think I've seen this before but didn't need it at the time so I didn't pay
attention,
But I every week I add a new value to the end of a row and then go in
manually add the new cell to the SUM function
example
first week
=SUM(A1:B1), then =SUM(A1:C1) then =SUM(A11) and so on...
How can the SUM to automatically ad the new cell to the total
And will this also work for the =AVERAGE(A1: B1), =AVERAGE(A1:C1) and so on
Thanks
James

 

[Ron de Bruin]

Why don't you use this for row 8

=SUM(8:8)
=AVERAGE(8:8)