If 27 December 2009 is given to be a Thursday, then what day of the week will it be on 1 March 2010?

Introduction / Context:
This question requires you to move forward in time from a known date and weekday to another date in the next year. You are told that 27 December 2009 is a Thursday and asked to find the day of the week on 1 March 2010. Such problems reinforce counting days across year boundaries and using the repeating cycle of seven days to track weekdays accurately.

Given Data / Assumptions:

• 27 December 2009 is a Thursday.
• We need to determine the day of the week on 1 March 2010.
• Year 2010 is not a leap year, so February 2010 has 28 days.
• Weekdays repeat every 7 days, and we use the Gregorian calendar.

Concept / Approach:
We will count how many days pass between 27 December 2009 and 1 March 2010, then compute the remainder when this count is divided by 7. That remainder tells us how many steps to move forward in the sequence of weekdays from Thursday. Since we cross from December to January and then to March, careful counting of days in each month is important.

Step-by-Step Solution:
Step 1: Days remaining in December 2009 after 27 December are 28, 29, 30, and 31, which is 4 days. Step 2: January 2010 has 31 days, and February 2010 has 28 days because 2010 is not a leap year. Step 3: From 1 January 2010 to 28 February 2010 inclusive there are 31 + 28 = 59 days. Step 4: From 27 December 2009 to 1 March 2010, the total number of days advanced is 4 (end of December) + 59 (January and February) + 1 additional day to reach 1 March, which sums to 64 days. Step 5: Compute 64 mod 7. Since 63 is divisible by 7, the remainder is 1. Step 6: A remainder of 1 means that we move one weekday forward from Thursday. Step 7: One day after Thursday is Friday. Therefore, 1 March 2010 is a Friday.

Verification / Alternative check:
Another method is to break the interval into easy chunks. From 27 December to 3 January is one week or 7 days, so weekday does not change when jumping by full weeks. Counting 7 day blocks wherever possible reduces mental load. For example, 64 days can be thought of as 63 days plus one day, where 63 days correspond to exactly 9 weeks that leave the weekday unchanged. The additional single day then shifts Thursday to Friday. This confirms the weekday without recalculating everything from scratch.

Why Other Options Are Wrong:
If we had obtained a remainder of 0 when dividing the total days by 7, the weekday would remain Thursday, which is not the case here. A remainder of 2 would have led to Saturday, and a remainder of 3 would have led to Sunday, but we found only a remainder of 1. Monday is also ruled out because it would require a remainder of 4. Therefore, Friday is the only option consistent with our modulo 7 calculation.

Common Pitfalls:
Mistakes often arise from miscounting the number of days in the months or forgetting to include or exclude the final day correctly. Another common error is computing the difference correctly but forgetting to take the remainder modulo 7, leading to unnecessary confusion. Candidates sometimes shift the weekday in the wrong direction, especially when they are not careful about whether time is moving forward or backward. Always verify that you are moving forward from the given date and not accidentally reversing the direction in your head.

Final Answer:
Thus, the day of the week on 1 March 2010, given that 27 December 2009 is a Thursday, is Friday.