Looking at Delaney's code, you could use something like this...

Code:
Public Class Form5

    Dim pairs As New Dictionary(Of TextBox, Button)

    Private Sub Form5_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        pairs.Add(TextBox1, Button6)
        pairs.Add(TextBox2, Button7)
        pairs.Add(TextBox3, Button8)
        pairs.Add(TextBox4, Button9)

        For Each kvp As KeyValuePair(Of TextBox, Button) In pairs
            AddHandler kvp.Key.KeyDown, AddressOf enter_keydown
            AddHandler kvp.Value.Click, AddressOf buttons_click
        Next
    End Sub

    Private Sub enter_keydown(ByVal sender As Object, ByVal e As KeyEventArgs)
        If e.KeyCode = Keys.Enter Then
            pairs(DirectCast(sender, TextBox)).PerformClick()
        End If
    End Sub

    Private Sub buttons_click(ByVal sender As Object, ByVal e As EventArgs)
        MsgBox(DirectCast(sender, Button).Text)
    End Sub
    
End Class