Have 12 rows of linked cells,
one for each month of the year.
End of the month, data for March, for
example is updated through a link to another
spreadsheet.
Months April - Dec have no data yet.
Two rows below the bottom of the twelve rows, is a simple
division calc, dividing cells D2/G2, for example.
At the end of the month I have to change the formula
(row 2 last month), to row 3 (D3/G3) for March,
next month same thing (D4/G4) until the end of the year.

Is there a lookup function that identifies the LAST
row of populated data in an array of data rows 1 - 12
and then performs the division?

Row
Jan 1
Feb 2
March 3
April 4
May 5
June 6
July 7
etc.