Public Class Form1
    Dim many As Integer = 0
    Dim total As Integer = 0
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        '////accumulate numbers into a total
        '///declarations
        Dim n As Integer 'the next input #
        
        'input: get # from textbox1
        n = Val(Me.TextBox1.Text)
        'processing:add n to total
        total = total + n
        many = many + 1
        'output: display the total(so far).
        Me.ListBox1.Items.Add("the total (so far) is: " & Format(total))

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        'compute and display the average
        Dim avg As Double

        'input:(none)
        '2.process:compute the average=total/many
        avg = total / many
        '3. output:display it
        Me.ListBox1.Items.Add("the average is " & avg)
    End Sub
End Class