Option Explicit

Sub scomponi()
Dim i As Integer, r As Range
    Set r = Selection
    For i = 1 To Len(r)
        r.Offset(, i) = Mid(r, i, 1)
    Next
End Sub

Option Explicit

Sub scomponi_2()
Dim v() As Variant, i As Integer

    ReDim v(Len([a1]) - 1)
    
    For i = 0 To Len([a1]) - 1
        v(i) = Array(i, 1)
    Next
    
    [a1].TextToColumns Destination:=[b1], DataType:=xlFixedWidth, FieldInfo:=v
    
End Sub

Option Explicit

Sub scomponi()
Dim intero As Integer, r As Range, ' variabile per colonna steep to steep rng As Range

  'Set rng = Sheets("Foglio1").Range("i3:B" & Range("i" & Rows.Count).End(xlUp).Row)
  
    Set r = Selection
    For intero = 1 To Len(r)
        r.Offset(, intero) = Mid(r, intero, 1)
    Next
    Set r = Nothing
End Sub

Option Explicit

Private Sub Worksheet_Change(ByVal Target As Range)
Dim i As Integer, r As Range, rng As Range

    'scompone il valore inserito nella cella che si sta editando
    'inserendo le diverse cifre che la copongono nelle colonne a destra
  
    If Intersect(Target, [I:I]) Is Nothing Then Exit Sub
    If Target.Row < 3 Then Exit Sub
    If Target = "" Then Exit Sub
    
    Application.EnableEvents = False
    
    Set r = Target
    For i = 1 To Len(r)
        r.Offset(, 17 + i) = Mid(r, i, 1)
    Next
    
    Application.EnableEvents = True
End Sub