property Calc.Buttons as String
Specifies the list of buttons in the control.

TypeDescription
String A string expression that indicates the list of buttons being displayed. The rows are separated by chr(13)+chr(10) ( vbCrLf ) sequence, and the buttons inside the row are separated by ';' character.
The Buttons property specifies the buttons and the layout of the buttons in the control. Use the PictureDown and PictureUp properties to specify the picture for the buttons. Use the ButtonHeight and ButtonWidth property to specify the height and the width of the buttons in the control. The ClickButton event occurs when the user clicks a button in the calculator. You can use the ButtonFromPoint property to get the button from the point. The DecimalSymbol property returns the current decimal symbol. The system's decimal symbol can be changed in your Control panel, under the Regional settings.

Each button supports built-in HTML format like follows:

By default, the Buttons property is "<fgcolor=0000FF><b>7</b></fgcolor>;<fgcolor=0000FF><b>8</b></fgcolor>;<fgcolor=0000FF><b>9</b></fgcolor>;<fgcolor=FF0000>/</fgcolor>;C\r\n<fgcolor=0000FF><b>4</b></fgcolor>;<fgcolor=0000FF><b>5</b></fgcolor>;<fgcolor=0000FF><b>6</b></fgcolor>;<fgcolor=FF0000>*</fgcolor>;1/x\r\n<fgcolor=0000FF><b>1</b></fgcolor>;<fgcolor=0000FF><b>2</b></fgcolor>;<fgcolor=0000FF><b>3</b></fgcolor>;<fgcolor=FF0000>-</fgcolor>;sqrt\r\n<fgcolor=0000FF><b>0</b></fgcolor>;<fgcolor=0000FF><b>+/-</b></fgcolor>;<fgcolor=0000FF><b>.</b></fgcolor>;<fgcolor=FF0000>+</fgcolor>;<fgcolor=000080><b>=</b></fgcolor>"

Use the Caption property to access the control's caption. Use the Execute method to execute operations inside the control. 

The following sample adds a new button 'sin' and execute the trigonometric sin function when 'sin' button is clicked:

Private Sub Form_Load()
    With Calc1
        .Buttons = .Buttons + vbCrLf + "<b>sin<b>"
    End With
End Sub
Private Sub Calc1_ClickButton(ByVal Button As String, Cancel As Variant)
    If (Button = "sin") Then
        With Calc1
            .Execute Sin(.Caption)
        End With
    End If
End Sub