On 8th Feb, 2005 it was Tuesday. What was the day of the week on 8th Feb, 2004?

### Concept & Backward Leap Day Crossing When calculating backward exactly one year, the day of the week subtracts 1 odd day for an ordinary year. However, if traversing backward forces you to cross February 29th, you must subtract 2 odd days. ### Step-by-Step Solution - We need to find the day for February 8, 2004, given February 8, 2005. - The year 2004 is a leap year (divisible by 4), which means it contains a February 29th. - Moving backward from Feb 8, 2005, to Feb 8, 2004, the timeline goes through March 2004, and crucially, it *includes* February 29, 2004, on its way back to February 8, 2004. - Because a leap day is crossed, the 1-year gap consists of 366 days. - 366 days $\equiv 2$ odd days. - Since we are moving backward in time, we subtract 2 odd days from Tuesday. - Tuesday - 2 days = Sunday. ### Exam Strategy & Shortcut When checking a 1-year gap involving a leap year, ask: "Is Feb 29th physically between my two dates?" Yes, Feb 29, 2004, sits between Feb 8, 2004, and Feb 8, 2005. Therefore, subtract 2. ### Common Pitfall Subtracting only 1 day because February 2004 is reached, without realizing that the leap day (Feb 29) was traversed in the journey backward. ### Final Answer Therefore, the correct answer is **Sunday**.