问C++\CLI DateTime计算误差

EN

long avgCycleTime;

DateTime startTime = DateTime::Now;

f1->textBox9->Text = startTime.ToString("dd/MM/yy  HH:mm:ss");
f1->textBox9->Update();

i = 0;  // cycle counter
while (i < nCycl)
{

    // this is where the simulation occurs

    i++;

    DateTime timeNow = DateTime::Now;
    TimeSpan timeLapsed = timeNow.Subtract(startTime);
    avgCycleTime = (timeLapsed.Ticks / i);
    DateTime estimEndTime = timeNow.AddTicks(avgCycleTime * (nCycl-i));

    f1->textBox10->Text = Convert::ToString(avgCycleTime / 10000000); // cycle time in milliseconds
    f1->textBox11->Text = estimEndTime.ToString("dd/MM/yy  HH:mm:ss");
    f1->Refresh();
}