Create 6 digit Random Number

using System.Text.RegularExpressions;

 Random adomRng = new Random();
        string rndString = string.Empty;
        char c;

        for (int i = 0; i < 6; i++)
        {
            while (!Regex.IsMatch((c = Convert.ToChar(adomRng.Next(48, 128))).ToString(), "[A-Za-z0-9]")) ;
            rndString += c;
        }

        string ss = rndString;