1st January 2000 AD = 1600 + 300 + 99 + 1 day Number of odd days in 1600 years = 0 Number of odd days in 300 years = 1 Number of odd days in 75 ordinary years = 75 Number of odd days in 24 leap years = 48 Number of odd days in January, 2000 = 1 Total number of odd days = 125 days = 17 weeks and 6 days Hence, 1 January 2000 AD was Saturday.