Finding the Last Row and using it in a formula

Question

I am dealing with a sheet of data that has multiple rows ans columns. Each time the macro runs, the number of rows can be different, so I am trying to find the last row for

Answer 1

Like so. Just remove the variable from the quotes.

Sub Output()

Dim LastRowA As Long

LastRowA = Worksheets("Sheet2").Cells(Rows.Count, "A").End(xlUp).Row

'this is my current method, it works using specific cells.
'I would like to change the D1662, for example, for a floating reference that gets the last row

Worksheets("Sheet2").Range("C2:C2").Formula = "='TIME SERIES'!D" & LastRowA & "/'TIME SERIES'!D2-1"

End Sub