Guru do Excel e Power BI

=REPT("0";16-NÚM.CARACT(A1))&A1

Private Sub Worksheet_Change(ByVal Target As Range)

Dim matriz() As Variant, w As Worksheet
Dim ulinha As Long
Dim tamanhoDaMatriz As Long
Dim vstringini As Long, vstringfim As String
Dim zerosFaltantes As Integer
Set w = ActiveSheet
If Target.Column = 1 And Target.Row > 1 Then
Application.ScreenUpdating = False
Application.EnableEvents = False
        ulinha = w.Cells(Cells.Rows.Count, 1).End(3).Row
        matriz = w.Range(Cells(2, 1), Cells(ulinha, 1)).Value
        
                For i = LBound(matriz()) To UBound(matriz())
                vstringfim = ""
                vstringini = VBA.Len(matriz(i, 1))
                
                zerosFaltantes = 16 - vstringini
                If zerosFaltantes = 16 Then GoTo nova_linha
                        If zerosFaltantes > 0 Then
                        
                        For a = 1 To zerosFaltantes
                        vstringfim = vstringfim & "0"
                        
                        
                        
                        Next a
                        
                        
                        End If
                vstringfim = vstringfim & matriz(i, 1)
                matriz(i, 1) = vstringfim
nova_linha:
                Next i



w.Range(Cells(2, 1), Cells(ulinha, 1)).Clear
w.Range(Cells(2, 1), Cells(UBound(matriz()) + 1, 1)).Value = matriz
Application.EnableEvents = True
Application.ScreenUpdating = True
End If


End Sub

Sub LeadingZeros()
 Dim c As Range
  For Each c In Range("A1", Cells(Rows.Count, 1).End(3))
   c.Value = Application.Rept(0, 16 - Len(c.Value)) & c.Value
  Next
End Sub