Simple Calculator W/O Classes

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            Dev_Pump.Text = "Made By: Dev_Pump";
            Dev_Pump.ReadOnly = true;
        }
        private void Addition_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Length == 0)
            {
                MessageBox.Show("You have not entered a number.");
            }
            else
            {
                //Calc values, Var
                int num1;
                int num2;
                float Answer;
                num1 = int.Parse(textBox1.Text);
                num2 = int.Parse(textBox2.Text);
                //Calc Add Start
                Answer = num1 + num2;
                textBox3.Text = Answer.ToString();
                SignL.Text = "+";
                ActionL.Text = "Action Used: Addition";
            }
        }

        private void Multiply_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Length == 0)
            {
                MessageBox.Show("You have not entered a number.");
            }
            else
            {
                //Calc values, Var
                int num1;
                int num2;
                float Answer;
                num1 = int.Parse(textBox1.Text);
                num2 = int.Parse(textBox2.Text);
                //Calc MultiP Start
                Answer = num1 * num2;
                textBox3.Text = Answer.ToString();
                SignL.Text = "X";
                ActionL.Text = "Action Used: Multiplcation";
            }
        }

        private void Subtract_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Length == 0)
            {
                MessageBox.Show("You have not entered a number.");
            }
            else
            {
                //Calc values, Var
                int num1;
                int num2;
                float Answer;
                num1 = int.Parse(textBox1.Text);
                num2 = int.Parse(textBox2.Text);
                //Calc SubT Start
                Answer = num1 - num2;
                textBox3.Text = Answer.ToString();
                SignL.Text = "-";
                ActionL.Text = "Action Used: Subtraction";
            }
        }

        private void Divide_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Length == 0)
            {
             MessageBox.Show("You have not entered a number.");
            }
                if (textBox1.Text.StartsWith ("0"))
                {
                    MessageBox.Show("WTF?.");
                }
                if (textBox2.Text.StartsWith("0"))
                {
                    MessageBox.Show("WTF?.");
                }
            else
            {
                //Calc values, Var
                int num1;
                int num2;
                float Answer;
                num1 = int.Parse(textBox1.Text);
                num2 = int.Parse(textBox2.Text);
                //Calc SubT Start
                Answer = num1 / num2;
                textBox3.Text = Answer.ToString();
                SignL.Text = "/";
                ActionL.Text = "Action Used: Division";
            }
        }
        private void TBox1(object sender, EventArgs e)
        {
            textBox1.Text = " ";
        }

        private void TBox2(object sender, EventArgs e)
        {
            textBox2.Text = " ";
        }
    }
}