10th November, 1981 A.D. was Tuesday. Which was the day on 11th November, 1581 A.D. ?

Correct option is D

Problem: Determine the day of the week on 11th November, 1581 A.D., given that 10th November, 1981 A.D., was a Tuesday.

Step 1: Calculate the Year Difference

The difference in years is:
1981 - 1581 = 400 years.

Step 2: Leap Year Rule

A leap year occurs if:
- The year is divisible by 4.
- However, years divisible by 100 are not leap years unless divisible by 400.

Thus, in a 400-year cycle, there are:
- 303 ordinary years (non-leap years)
- 97 leap years.

Step 3: Total Days in 400 Years

Each ordinary year adds 1 extra day, and each leap year adds 2 extra days.

The total days contributed by 400 years are:
(303 × 1) + (97 × 2) = 303 + 194 = 497 days.

Since 497 mod 7 = 0, the days cycle repeats exactly every 400 years.

Step 4: Determine the Day for 11th November, 1581

- 10th November, 1981 is a Tuesday.
- Since the day cycle repeats every 400 years, 10th November, 1581 will also be a Tuesday.
- Therefore, 11th November, 1581, will be the day after Tuesday, which is Wednesday.

Final Answer

The day on 11th November, 1581, was **Wednesday**.