ช่วยหาวิธีคำนวณในไปแสดงบนTextboxใหญ่ๆหน่อยนะครับไม่รู้จะเอาตัวแปรไหนมาโชว์มาแสดงช่วยหน่อยนะครับขอบคุณครับ

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

        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            if ((e.KeyChar < 48) || (e.KeyChar > 57))
            {
                e.KeyChar = Convert.ToChar(Keys.Back);
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
                textBox1.Text = "";
                textBox2.Text = "";
                textBox3.Text = "";
        }

        private void button2_stop_Click(object sender, EventArgs e)
        {
            this.Close();
        }

       private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            textBox2.Clear();
            string a = textBox1.Text;
            try
            {
                
                int b = Convert.ToInt32(listBox1.Text);
                string c = Convert.ToString(bin(b, int.Parse(a)));
                if (c == "0")
                {
                    switch (a)
                    {
                        case "10": a = "A"; break;
                        case "11": a = "B"; break;
                        case "12": a = "C"; break;
                        case "13": a = "D"; break;
                        case "14": a = "E"; break;
                        case "15": a = "F"; break;
                    }
                    textBox2.Text = a + "";
                }
                string m = Convert.ToString(int.Parse(a) % (int.Parse(c) * b));
                while (int.Parse(c) >= b)
                {
                        m = Convert.ToString(int.Parse(a) % (int.Parse(c) * b));
                        switch (m)
                        {
                            case "10": m = "A"; break;
                            case "11": m = "B"; break;
                            case "12": m = "C"; break;
                            case "13": m = "D"; break;
                            case "14": m = "E"; break;
                            case "15": m = "F"; break;
                        }
                        textBox2.Text = m + " " + textBox2.Text + " "; 
                        
                        a = c;
                        c = Convert.ToString(bin(b, int.Parse(c))); 
                   
                }
                m = Convert.ToString(int.Parse(a) % (int.Parse(c) * b));
                switch (m)
                {
                    case "10": m = "A"; break;
                    case "11": m = "B"; break;
                    case "12": m = "C"; break;
                    case "13": m = "D"; break;
                    case "14": m = "E"; break;
                    case "15": m = "F"; break;
                }
                switch (c)
                {
                    case "10": c = "A"; break;
                    case "11": c = "B"; break;
                    case "12": c = "C"; break;
                    case "13": c = "D"; break;
                    case "14": c = "E"; break;
                    case "15": c = "F"; break;
                }
                textBox2.Text = c + " " + m + " " + textBox2.Text + " ";
                textBox2.Text = textBox2.Text;
            }
            catch { }
           
           
        }

        private int bin(int b, int a)
        {
            int x = 0;
            int i = 1;
            while (true)
            {
                x = b * i;
                if (x > a)
                    break;
                i++;
            }
            if (i * b > a)
            {
                i--;
            }
            x = i;
            return x;   
        }
    }

 }



//โค๊ดผมประมาณนี้ครับ อยากทราบตัวแปรที่จะนำมาแสดงให้มันเป็นวิธีการคำนวณออกมาเราเห็นบน Textboxของวิธีการคำนวณอะครับ