Public Class Form1
    '========= INPUT METHODS:
    Function getFirst() As Integer
        '''' Get 1st # 
        Return Val(TxtFirst.Text)
    End Function
    Function getSecond() As Integer
        '''' Get 1st #
        Return Val(TxtFirst.Text)
    End Function


    '========= OUTPUT METHODS:
    Sub saywhat(ByVal s As String, ByVal v As Integer)
        '''' Display msg & #
        Me.ListBox1.Items.Add(s & Format(v))
    End Sub

    Private Sub button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        '''' lo button handler:  input 2 #s, add them, display answer
        Dim low As String = "The sum is  "      '// (Change this) Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label.Click


        '''' INPUT:
        Dim lo, hi As Integer
        low = getFirst()
        hi = getSecond()


        '''' PROC:
        Dim answer As Integer
        answer = countdown(lo, hi)      '// (Change this)

        '''' OUTPUT:
        saywhat(lo, hi)
    End Sub

    

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        '???

        Dim low As Integer
        Dim hi As Integer
        low = getFirst()
        hi = getSecond()
        Me.BackColor = Color.Red

    End Sub

    Private Sub Label_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label.Click

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        '''' Add button handler:  input 2 #s, countup them, display answer
        Dim s As String = "The difference is  "      '// (Change this)

        '''' INPUT:
        Dim a, b, c As Integer
        lo = getFirst()
        hi = getSecond()


        '''' PROC:
        Dim answer As Integer
        answer = calcSub(a, b)      '// (Change this)

        '''' OUTPUT:
        saywhat(s, answer)

    End Sub
    Function calcSub(ByVal a As Integer, ByVal b As Integer) As Integer
        '''' countup the 2 #s
        Dim result As Integer
        result = lo - hi          '(Change this for each different op.)
        Return result
    End Function


End Class
    End Sub

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click

    End Sub