Code analysis/review

using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
int a, b,sonuc=0;
a = Convert.ToInt32(textBox1.Text);
b = Convert.ToInt32(textBox2.Text);
sonuc = a + b;
label3.Text = sonuc.ToString();

}

private void button2_Click(object sender, EventArgs e)
{
int a, b, sonuc = 0;
a = Convert.ToInt32(textBox1.Text);
b = Convert.ToInt32(textBox2.Text);
sonuc = a – b;
label3.Text = sonuc.ToString();
}

private void button3_Click(object sender, EventArgs e)
{
int a, b, sonuc = 0;
a = Convert.ToInt32(textBox1.Text);
b = Convert.ToInt32(textBox2.Text);
sonuc = a / b;
label3.Text = sonuc.ToString();
}

private void button4_Click(object sender, EventArgs e)
{
int a, b, sonuc = 0;
a = Convert.ToInt32(textBox1.Text);
b = Convert.ToInt32(textBox2.Text);
sonuc = a*b;
label3.Text = sonuc.ToString();
}
}
}