CODIGO CALCULADORA SIMPLE

Public Class Form2
    Dim guarda As Integer = 0
    Dim signo As String

    Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click
        operador("/")
    End Sub
    Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
        operador("*")
    End Sub
    Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
        operador("-")
    End Sub
    Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
        operador("+")

    End Sub

    Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub
    Sub calcular(ByVal valor)
        If Txtpantalla.Text = "+" Or Txtpantalla.Text = "-" Or Txtpantalla.Text = "*" Or Txtpantalla.Text = "/" Then
            Txtpantalla.Text = ""
            Txtpantalla.Text = Txtpantalla.Text + CStr(valor)
        Else

            Txtpantalla.Text = Txtpantalla.Text + CStr(valor)
        End If
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        calcular(1)
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        calcular(2)
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        calcular(3)
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        calcular(4)
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        calcular(5)
    End Sub

    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        calcular(6)
    End Sub

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        calcular(7)
    End Sub

    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        calcular(8)
    End Sub

    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
        calcular(9)

    End Sub

    Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
        calcular(0)

    End Sub
    Sub operador(ByVal oper)
        signo = oper
        guarda = CInt(Txtpantalla.Text)
        Txtpantalla.Text = signo

    End Sub

    Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
        Select Case signo
            Case "+"
                Txtpantalla.Text = CStr(guarda + CInt(Mid(Txtpantalla.Text, 1)))
            Case "-"
                Txtpantalla.Text = CStr(guarda - CInt(Txtpantalla.Text))
            Case "*"
                Txtpantalla.Text = CStr(guarda * CInt(Txtpantalla.Text))
            Case "/"
                Txtpantalla.Text = CStr(guarda / CInt(Txtpantalla.Text))
        End Select
    End Sub
End Class