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

Here's an overkill method, literally just for fun (don't downvote me for having a little fun with VBA - this is actually useful to know how to do). It adds a data validation list to a range that only allows a number followed by an uppercase letter. I do this by quite literally adding every single combination allowable :) Of course you don't have to SELECT form the list, but if you try to type something that's not allowed, you get the buzzer :)

Sub AddValidation()

Dim cell As Range
Dim dict As Object
Set dict = CreateObject("scripting.dictionary")
Dim alphabet As String, numbers As String
alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
numbers = "1234567890"
Dim validList As String

For i = 1 To Len(numbers)
    For j = 1 To Len(alphabet)
        dict.Add Mid$(numbers, i, 1) & Mid$(alphabet, j, 1), 1
    Next
Next

validList = Join(dict.keys, ", ")

'Example using B1:B10
With Range("B1:B10").Validation
    .Delete
    .Add Type:=xlValidateList, _
    AlertStyle:=xlValidAlertStop, Operator:= _
    xlBetween, Formula1:=validList
    .IgnoreBlank = True
    .InCellDropdown = True
    .InputTitle = ""
    .ErrorTitle = ""
    .InputMessage = ""
    .ErrorMessage = "Invalid data entered"
    .ShowInput = True
    .ShowError = True
End With

End Sub