According to the question, 27th December, 2009 is Thursday Number of days left in December = 31 - 27 = 4 Similarly, odd days from 27th December, 2009 till 1st March, 2010 = ( 4 + 31+ 28 + 1 ) % 7 = 4 + 3 + 0 + 1 = 8 Now, dividing 8 by 7, remainder = 1 Thus, day on 1st March, 2009 = Thursday (+1) = Friday