private void btnsubtract_Click(object sender, EventArgs e)
{
operador = "-";
primero = double.Parse(CalcScreen.Text);
CalcScreen.Clear();
}
private void btnmultiplication_Click(object sender, EventArgs e)
{
operador = "*";
primero = double.Parse(CalcScreen.Text);
CalcScreen.Clear();
}
private void btnCE_Click(object sender, EventArgs e)
{
CalcScreen.Clear();
}