This seems so simple I'm almost embarressed to ask but:
I have a form where I want a text box to display the total of the textbox values on the form.

[vba]Private Sub Calculate()
On Error Resume Next
TextBox3.Value = TextBox1.Value + TextBox2.Value
' TextBox3.Value = (Format(TextBox, "0.00"))
End Sub
Private Sub TextBox1_Change()
OnlyNumbers
Calculate
End Sub
Private Sub TextBox2_Change()
OnlyNumbers
Calculate
End Sub

Private Sub OnlyNumbers()
If TypeName(Me.ActiveControl) = "TextBox" Then
With Me.ActiveControl
If Not IsNumeric(.Value) And .Value <> vbNullString Then
MsgBox "Sorry, only numbers allowed"
.Value = vbNullString
End If
End With
End If

End Sub[/vba]
This works when multiplying the values
[vba]TextBox3.Value = TextBox1.Value * TextBox2.Value[/vba]
So i must be in the right area???

As an add on I would like the total to be rounded to be the sum of textbox1 and textbox2, divided by 1000 and dsiplayed to 2 figures

eg

1234 + 3456 = 4.69