Excel : Data Validation, how to force the user to enter a string that is 2 char long?

Question

I would like to add some data validation on a cell in the latest Excel. I would like to force the user to enter a string that is two-char long, with the first char a digit,

Answer 1

If you can use VBA then try to catch event Worksheet_Change:

Private Sub Worksheet_Change(ByVal Target As Range)
    MsgBox "You just changed " & Target.Address
    ' your logic goes here
End Sub