A ještě jeden:

private void button16_Click(object sender, EventArgs e)
{
if (clear == 3 || clear == 4 || clear == 5)
label2.Text = label2.Text = " / ";
else label2.Text = label2.Text = label1.Text + " / ";
label1.Text = eval(op).ToString();
op = "/";
}

private void button17_Click(object sender, EventArgs e)
{

if (clear != 3 && clear != 4 && clear != 5)
label2.Text = label2.Text + label1.Text;
label1.Text = eval(op).ToString(); clear = 2;
}


private void button12_Click(object sender, EventArgs e)
{
Clear(2); clear = 1; label1.Text = "0"; result = 0;
[/code]