C# PC On time calculation code

String cevap = String.Empty;
            cevap += Convert.ToString(Environment.TickCount / 86400000) + "day, ";
            cevap += Convert.ToString(Environment.TickCount / 3600000 % 24) + " hour, ";
            cevap += Convert.ToString(Environment.TickCount / 120000 % 60) + " minute, ";
            cevap += Convert.ToString(Environment.TickCount / 1000 % 60) + " second.";
            label1.Text = cevap;