Option Explicit
    Dim Value1 As Double
    Dim Value2 As Double
    Dim Value3 As Double

Private Sub cmdAdd_Click(Index As Integer)

    Value3 = Value1 + Value2
    
End Sub

Private Sub Form_Load()

    txtV1.Text = Value1
    txtV2.Text = Value2
    txtOutput.Text = Value3
    
End Sub

txtV1.Text = Str(Value1)

Public Sub AddC(RTB As RichTextBox, ParamArray saElements() As Variant)
With RTB
    RTBName = .Name
End With
    Dim i As Integer
        With RTB
        .SelStart = 999999999
        .SelLength = 0
        .SelColor = &HE0E0E0
        .SelText = "[" & Format(Time, "hh:mm:ss") & "] "
        .SelStart = 999999999
        End With
    For i = LBound(saElements) To UBound(saElements) Step 2
        With RTB
        .SelStart = 999999999
        .SelLength = 0
        .SelColor = saElements(i)
        .SelText = saElements(i + 1) & Left$(vbCrLf, -2 * CLng((i + 1) = UBound(saElements)))
        .SelStart = 999999999
        End With
    Next i
With RTB
If Len(.Text) >= 10000 Then
.SelStart = 0
.SelLength = 10000
.SelText = ""
.SelLength = 10000
.SelStart = Len(.Text)
End If
If Len(.Text) >= 5000 Then
.SelStart = 0
.SelLength = 2500
.SelText = ""
.SelLength = 5000
.SelStart = Len(.Text)
End If
.Refresh
End With
End Sub

Option Explicit
    Dim Value1 As Double
    Dim Value2 As Double
    Dim Value3 As Double

Private Sub Add_Click(Index As Integer)
    Value3 = Value1 + Value2
End Sub

Private Sub Form_Load()
    V1(0).Text = Value1
    V2(1).Text = Value2
    Output.Text = Value3
End Sub