How to automatically change the the sheet reference not including the formula by dragging down the cell?

[shekel balanon]

Hello,

I am a newbie here.

May I ask for your help? How do I automatically change the sheet reference but not the formula?
The formula I'm using is =SUM('1'!C8:C35).
And when I drag it downwards, I want the sheet reference to become '2'

 

[Joe4]

Welcome to the Board!

Let's say that you are putting the first formula in row 5. Then use this formula:

=SUM(INDIRECT("'" & ROW()-4 & "'!C8:C35"))

and copy down.

Just change the "4" in the formula to one less than the row number the first formula is going in.