//shows different options for adding numbers from textboxes
 
 private void button1_Click(object sender, EventArgs e)
        {


            //wrong answer!
            
            label1.Text = textBox1.Text + textBox2.Text;
            
            //fails
            label1.Text = Convert.ToSingle(textBox1.Text) + Convert.ToSingle(textBox2.Text);
            
            //works
            label1.Text = Convert.ToString(Convert.ToSingle(textBox1.Text) + Convert.ToSingle(textBox2.Text));
            

            //with variables

            int firstNumber = Convert.ToInt16(textBox1.Text);
            int secondNumber =Convert.ToInt16(textBox2.Text);
            int result = firstNumber + secondNumber;
            label1.Text = result.ToString();

            
            //all in one line
            int result = Convert.ToInt16(textBox1.Text) + Convert.ToInt16(textBox2.Text);
            label1.Text = result.ToString();
        }