Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim a, b, c As Single, oper As String
        a = Rnd() * 300 : b = Rnd() * 200
        TextBox1.Text = Format(a, "###.#")
        TextBox2.Text = Format(b, "###.#")
        oper = InputBox("Введите название операции", "Операция")

        If oper = "сложение" Then
            c = a + b
            TextBox4.Text = Format("+")

        End If
        If oper = "вычитание" Then
            c = a - b
            TextBox4.Text = Format("-")

        End If
        If oper = "умноженние" Then
            c = a * b
            TextBox4.Text = Format("*")
        End If
        If oper = "деление" And b <> 0 Then
            c = a / b
            TextBox4.Text = Format(c, "######.####")

        End If
        TextBox4.Text = Format(c, "######.####")
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Me.Close()
    End Sub
End Class