Help I'm tearing my hair out

sing System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Humanizer; //@#$! PROJECT EULER!!!!
                 /*
                  * Write a program that prints out check amounts in words:
                  * For example $1,234 would print as:
                  * “one thousand two hundred thirty four dollars”.
                  * $9,017 would print as: "nine thousand seventeen dollars".
                  * Handle amounts up to $9,999.  Disregard printing cents.
                  * Suggestion: try using arrays instead of lengthy "if" statements.
                  * Remember, the less code you write, the less to debug.
                 */




namespace ConvertDigitsToWords {
    public class Program {

        public static void Main(string[] args) {
            //TODO: Add error handleing here, or change to Int32.TryParse
            //If I can remember how the @#$%! to use it.

            string input;
            uint number;
            bool isValid;
            Console.WriteLine("\nEnter 0 to quit the program at any time\n");

            do {
                Console.WriteLine("Enter integer greater than 0");
                input = Console.ReadLine();
                isValid = uint.TryParse(input, out number);

                if (!isValid) {
                    Console.WriteLine("\n Not an Integer, Please try again\n");
                }
                else {
                    //Console.WriteLine("\n {0}\n", NumberToText(number));
                    Humanizer.NumberToWordsExtension.ToWords((int)number);
                    //Yes I cheated, Kept getting an Index out of bounds
                    //exception explanation below where the excepton has happened.
                }//end if
            } while (!(isValid && number == 0));

            Console.ReadLine();
        } //End Main

        public static string NumberToText(uint number) {
            if (number == 0)
                return "Zero";
            uint[] num = new uint[4];
            uint first = 0;
            uint u, h, t;
            StringBuilder sb = new StringBuilder();
            string[] words0 = { "", "One ", "Two ", "Three ", "Four ", "Five ", "Six ", "Seven ", "Eight ", "Nine " };
            string[] words1 = { "Ten ", "Eleven ", "Twelve ", "Thirteen ", "Fourteen ", "Fifteen ", "Sixteen ", "Seventeen ", "Eighteen ", "Ninteen " };
            string[] words2 = { "Twenty ", "Thirty ", "Fourty ", "Fifty ", "Sixty ", "Seventy ", "Eighty ", "Ninety " };
            string[] words3 = { "Thousand ", "Million ", "Billion " };

            num[0] = number % 1000; //units
            num[1] = number / 1000;
            num[2] = number / 1000000;
            num[1] = num[1] - 1000 * num[2]; //thousands
            num[3] = number / 1000000000; //billions
            num[2] = num[2] - 1000 * num[3]; //millions

            for (uint i = 3; i > 0; i--) {
                if (num[1] != 0) {
                    /*
                     *
                     * Getting IndexOutOutOfBounds
                     * Exception Here, if you could please
                     * Help explain the logic behind this
                     * I would apprecaiate it
                     * I've used Step into several
                     * times on the
                     * debugger and it seems like
                     * for some reason first
                     * gets set to number
                     * instead of "i"
                     */
                    first = i;
                    break;
                }//end if
            }//end for

            for (uint i = first; i >= 0; i--) {
                if (num[i] == 0) { continue; }
                u = num[i] % 10; // ones
                t = num[i] / 10;
                h = num[i] / 100; //hundreds
                t = t - 10 * h; //tens
                if (h > 0) {
                    sb.Append(words0[h] + "Hundred ");
                }//end if
                if (u > 0 || t > 0) {
                    if (t == 0)
                        sb.Append(words0[u]);
                    else if (t == 1)
                        sb.Append(words1[u]);
                    else
                        sb.Append(words2[t - 2] + words0[u]);
                } //end if
                if (i != 0) {
                    sb.Append(words3[i - 1]);
                }//end if
            }//End For
            return sb.ToString().TrimEnd();
        } //end Number to Text
    } //end Class
} //end Namespace