On 1st Jan 2004 thursday falls What day of the week was it on 1st Jan 2005 ........

Explanation:

Given that January 1, 2004  was Thursday.

2004 is a leap year. Therefore odd days in 2004=2

2004=2 (complete year 2004 is considered because we are taking dates from 1-Jan-2004 to 31-Dec-2004)

Hence January 1, 2005= (Thursday + 2 odd days) = Saturday