From 17 December 2002 (Saturday) to 17 December 2004 is 2 years including 1 leap year (2004). Total days = 365 + 366 = 731 days. 731/7 = 104 weeks and 3 days. So 17 December 2004 is 3 days after Saturday = Tuesday. From 17 December 2004 (Tuesday) to 22 December 2004 is 5 days. Tuesday + 5 days = Sunday.