Get the range of the last X rows in Google Sheets

Question

Say I have a spreadsheet with 18 rows, and I can hard code the range of the last 7 values in column D and average their values like so:

=AVERAGE(D12:D18)

How then could I do the same without hard coding them, so it'll work as I add more rows?

Answer 1

If you want to calculate the average or sum, there's no need for a script. You can accomplish this with an array filter as well. The following formula calculates the average over the last 7 rows in the A column:

=AVERAGE(FILTER(A:A;ARRAYFORMULA(ROW(A:A)>COUNT(A:A)-7+1)))

This assumes that the data starts at row 1. Otherwise you have to change the latter constant in the formula to the row number where the data starts.