Public Class Form1
    Inherits System.Windows.Forms.Form

    Const addAmount As Double = 10

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    Friend WithEvents TxtInput As System.Windows.Forms.TextBox
    Friend WithEvents txtOutput As System.Windows.Forms.TextBox
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents BtnCalc As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.TxtInput = New System.Windows.Forms.TextBox
        Me.txtOutput = New System.Windows.Forms.TextBox
        Me.Label1 = New System.Windows.Forms.Label
        Me.Label2 = New System.Windows.Forms.Label
        Me.BtnCalc = New System.Windows.Forms.Button
        Me.SuspendLayout()
        '
        'TxtInput
        '
        Me.TxtInput.Location = New System.Drawing.Point(168, 24)
        Me.TxtInput.Name = "TxtInput"
        Me.TxtInput.Size = New System.Drawing.Size(104, 20)
        Me.TxtInput.TabIndex = 0
        Me.TxtInput.Text = ""
        '
        'txtOutput
        '
        Me.txtOutput.Location = New System.Drawing.Point(168, 72)
        Me.txtOutput.Name = "txtOutput"
        Me.txtOutput.ReadOnly = True
        Me.txtOutput.Size = New System.Drawing.Size(104, 20)
        Me.txtOutput.TabIndex = 1
        Me.txtOutput.Text = ""
        '
        'Label1
        '
        Me.Label1.Location = New System.Drawing.Point(72, 24)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(80, 16)
        Me.Label1.TabIndex = 2
        Me.Label1.Text = "Input"
        '
        'Label2
        '
        Me.Label2.Location = New System.Drawing.Point(72, 72)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(80, 16)
        Me.Label2.TabIndex = 3
        Me.Label2.Text = "Output"
        '
        'BtnCalc
        '
        Me.BtnCalc.Location = New System.Drawing.Point(160, 120)
        Me.BtnCalc.Name = "BtnCalc"
        Me.BtnCalc.Size = New System.Drawing.Size(72, 32)
        Me.BtnCalc.TabIndex = 4
        Me.BtnCalc.Text = "Calculate"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 273)
        Me.Controls.Add(Me.BtnCalc)
        Me.Controls.Add(Me.Label2)
        Me.Controls.Add(Me.Label1)
        Me.Controls.Add(Me.txtOutput)
        Me.Controls.Add(Me.TxtInput)
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub BtnCalc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnCalc.Click
        Dim input As Double
        If IsNumeric(TxtInput.Text) Then
            input = Convert.ToDouble(TxtInput.Text)
            If (input > 0) And (input <= 200) Then
                ' input is valid
                Dim output As Double
                output = input + addAmount
                txtOutput.Text = output.ToString("c")
            Else
                MsgBox("Please enter a price betweeen 0 and 200")

            End If
        Else
            MsgBox("You idiot, enter a number")
        End If

    End Sub
End Class