I have a trend chart showing the last 12 months, the point is that I needed to calculate for instance the percentage between the last month and the first month and since the last cell of a column and/or of a row is updated every month, this macro will look for it and update the formula.

When I use the macro ?

To find the last cell of a row and/or of a column in order to update the formula.

How to create the macro ?

Read How to create, edit, hide and select a macro in an excel report

How to create the button to associate it with the macro ?

Read How to create a button and associated it to a macro in an excel report

How is/are the macro(s) ?

Copy the code below and paste it into your macro. You will see my comments in green if exist so follow the help to adapt to your need.

For the column, for instance, in the cell D2, I have this formula:

=B13/B2- 1

Sub test()
Dim i As Integer
Dim j As Integer
i = Cells(Rows.Count, 2).End(xlUp).Row
' change 11 if you want less or more months
j = (Cells(Rows.Count, 2).End(xlUp).Row) - 11
' change D2 by your cell and B by your column letter
Range("D2") = "=B" & i & "/B" & j & "- 1"
End Sub

For the row, for instance, in the cell A2, I have this formula:

=SUM(B2:M2)

Sub test()
Dim i
Dim j
' change A1 by the first cell of your row where you want to check
i = Split(Columns(Range("A1").End(xlToRight).Column).Address(, False), ":")(1) 
' change 11 if you want less or more months
j = Split(Cells(1, Range(i & 1).Column - 11).Address, "$")(1) 
' change A4 by your cell and 2 by your row number 
Range("A5") = "=SUM(" & j & "2:" & i & "2)" 
End Sub