NUMBERS STRING REPRESENTATION(MATI)

static void Main(string[] args)
        {
            Console.WriteLine("Enter a number in the range 0-999");
            int input = int.Parse(Console.ReadLine());

            string answer = NumberToText(input);
            Console.WriteLine(answer);

            Console.ReadKey();
        }

        static public string NumberToText(int x)
        {
            string answer = "";

            string y = "" + x;
            char[] number = y.ToCharArray();
            int len = number.Length;


            if (Check(x) == false)
            {
                answer = "Number is invalid";
                return answer;
            }
            else
            {
                string[] ones = new string[] { "", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine" };
                string[] teens = new string[] { "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen" };
                string[] tens = new string[] { "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety" };

                if (x == 0)
                {
                    answer = "Zero";
                    return answer;
                }
                else
                {
                    if (len == 1)
                    {
                        int p1 = Convert.ToInt16(number[0]) - 48;
                        answer = ones[p1];
                        return answer;
                    }

                    else if (len == 2)
                    {
                        int p1 = Convert.ToInt16(number[0]) - 48;
                        int p2 = Convert.ToInt16(number[1]) - 48;

                        if (x >= 20)
                        {
                            answer = tens[p1 - 2] + "-" + ones[p2];
                            return answer;
                        }
                        else
                        {
                            answer = teens[x - 10];
                            return answer;
                        }
                    }
                    else
                    {
                        int p1 = Convert.ToInt16(number[0]) - 48;
                        int p2 = Convert.ToInt16(number[1]) - 48;
                        int p3 = Convert.ToInt16(number[2]) - 48;

                        if (p2 >= 2)
                        {
                            answer = ones[p1] + " Hundred " + tens[p2 - 2] + " " + ones[p3];
                            return answer;
                        }
                        else
                        {
                            int teen = p2 * 10 + p3;
                            answer = ones[p1] + " Hundred " + teens[teen - 10];
                            return answer;
                        }
                    }
                }
            }
        }

        static public bool Check(int x)
        {
            bool valid;

            if (x < 0 || x > 999)
            {
                valid = false;
                return valid;
            }
            else
            {
                valid = true;
                return valid;
            }
        }