sumproduct last 30 rows

[Guest]

How can I use sumproduct on the last 30 rows of a database whose number of
rows changes daily?

 

[vezerid]

Assuming your headings are in row 1 and data start from row 2 and
down. To sum column C:C, one way:

=SUMPRODUCT(OFFSET(C1,COUNTA(C:C)-29,0,30,))

HTH
Kostis Vezerides

 

[Guest]

Assume your data in column A and header in row1, and no "blank" cells in
between the data

=SUM(OFFSET(A2,COUNT(A:A)-1,,-30,1))