Calculadora basica

Public Class Form1 Private Sub Button20_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Btnlimpiar.Click txtpantalla.Clear() End Sub Private Sub Button19_Click(ByVal senderAs System.Object, ByVal e As System.EventArgs) Handles btnapagar.Click txtpantalla.Enabled = False If btnapagar.Text = "cerrar" Then Close() End If btnapagar.Text = "cerrar" End Sub Private SubButton4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnsuma.Click n1 = txtpantalla.Text opera = 1 txtpantalla.Clear() End Sub Private Sub Button17_Click(ByVal sender AsSystem.Object, ByVal e As System.EventArgs) Handles btnraiz.Click Dim raiz As Double resp = 0 n1 = Val(txtpantalla.Text) raiz = Math.Sqrt(n1) txtpantalla.Text = raiz End Sub Private Subtxtpantalla_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtpantalla.TextChanged End Sub Private Sub Button18_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handlesbtnencender.Click txtpantalla.Enabled = True btnapagar.Text = "apagar" End Sub Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Btn7.Click txtpantalla.Text= txtpantalla.Text + "7" End Sub Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Btn1.Click txtpantalla.Text = txtpantalla.Text + "1" End Sub Private SubButton6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Btn2.Click

txtpantalla.Text = txtpantalla.Text + "2" End Sub Private Sub Button7_Click(ByVal sender AsSystem.Object, ByVal e As System.EventArgs) Handles Btn3.Click txtpantalla.Text = txtpantalla.Text + "3" End Sub Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handlesbtn4.Click txtpantalla.Text = txtpantalla.Text + "4" End Sub Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn5.Click txtpantalla.Text = txtpantalla.Text...