Number of odd days till 2000 is 0.
Number of odd days from 2001 to 2009 is 10( 2 leap years +6 normal years).
Number of odd days in 2010 till sept 10 is (31+28+31+30+31+30+31+31+30 = 274) 274
Total odd days is 274+10=284%7=4.
So, the day is thursday.