What was the day of the week on 17th August, 2010?

Period upto 17th August, 2010 = (2009 yr + Period from 1.1.2010 to 17.8. 2010)

Counting of odd days
Odd day in 1600 yr = 0
Odd days in 400 yr = 0
9 yr = (2 leap years + 7 ordinary years)
= ( 2 x 2 + 7 x 1) = 1 week + 4 days = 4 odd days

Number of days between 1.1.2010 to 17.8.2010
January + February + March + April + May + June + July + August.
= (31 + 28 + 31 + 30 + 31 + 30 + 31 + 17) days
= 229 days = 32 weeks + 5 odd days

Total number of odd days = (0 + 0 + 4 + 5 ) days
= 9 days = 1 week + 2 odd days
Hence, the required day is Tuesday.