kalkulator tanpa menggunakan keypress

Private Sub cmdbatal_Click()
txtn1 = ""
txtn2 = ""
txtn3 = ""
txtn4 = ""
txtn5 = ""
txtn6 = ""
txtn7 = ""
txtn8 = ""
txttotal1 = ""
txttotal2 = ""
txttotal3 = ""
txttotal4 = ""
txtn1.SetFocus
End Sub

Private Sub cmdhitung_Click()
txttotal1 = Val(txtn1) + Val(txtn2)
txttotal2 = Val(txtn3) / Val(txtn4)
txttotal3 = Val(txtn5) - Val(txtn6)
txttotal4 = Val(txtn7) * Val(txtn8)
End Sub

Private Sub cmdkeluar_Click()
Unload Me

End Sub

Private Sub cmdlagi_Click()
txtn1 = ""
txtn2 = ""
txtn3 = ""
txtn4 = ""
txtn5 = ""
txtn6 = ""
txtn7 = ""
txtn8 = ""
txttotal1 = ""
txttotal2 = ""
txttotal3 = ""
txttotal4 = ""
txtn1.SetFocus

End Sub