When you say "up to 911" I presume you mean "up to September 11th". WaldoMcFroog's assumption is wrong; the millennium started on 1st January 2001. Therefore the answer is 254. If you menat "up to the 911th day of the millennium" then the answer is 30th June 2003.
Read the answer Bernardo. I said 'assuming you base', since the vast majority of people do count the Millennium from that date. I am well aware of the correct start of the Millennium.