Using the standard Gregorian calendar, on which day of the week did 28th May 2006 fall?

Introduction / Context:
This question asks you to determine the day of the week for a specific historical date: 28th May 2006. Calendar problems like this are common in competitive exams and can be solved using methods such as counting odd days, Zeller’s congruence, or by using a known reference date for the same year.

Given Data / Assumptions:

• Date of interest: 28th May 2006.
• Calendar: standard Gregorian calendar.
• 2006 is a non-leap year (since 2006 is not divisible by 4).
• We will rely on standard month-length values for 2006:
  • January: 31 days
  • February: 28 days
  • March: 31 days
  • April: 30 days
  • May: 31 days

Concept / Approach:
One approach is to use a known reference weekday for a specific date in 2006 and count forwards or backwards modulo 7 to reach 28th May 2006. Another structured way is the odd-days method: we compute how many days have passed from a base date such as 1st January 2006 up to 28th May 2006 and then convert that into the weekday shift. For this explanation, we will rely on the concept that 1st January 2006 fell on a Sunday.

Step-by-Step Solution:
Step 1: It is known (and verifiable) that 1st January 2006 fell on a Sunday. Step 2: Calculate the number of days from 1st January to 28th May 2006. Step 3: Days in January = 31, February = 28, March = 31, April = 30. Step 4: Up to 30th April, total days = 31 + 28 + 31 + 30 = 120 days. Step 5: Add days in May up to 28th: 28 days. Step 6: Total days from 1st January to 28th May inclusive = 120 + 28 = 148 days; days after 1st January = 147 days. Step 7: 147 mod 7 = 0, because 147 = 21 * 7. Step 8: A remainder of 0 means we have completed full weeks; the weekday is the same as on 1st January 2006. Step 9: Therefore, 28th May 2006 falls on a Sunday.

Verification / Alternative check:
You can confirm the answer by consulting a reliable perpetual calendar or by using Zeller's congruence specifically for 28-05-2006, which also returns Sunday as the day of the week. Checking nearby known dates such as 1st May 2006 (Monday) and then counting within May confirms that 28th May lands on a Sunday.

Why Other Options Are Wrong:
Thursday, Friday, Saturday and Monday all represent weekday shifts that would require a non-zero remainder when the days from the reference date are divided by 7. Since we obtained a remainder of 0, the weekday must coincide exactly with the weekday of 1st January 2006, which is Sunday, and not any of the other listed days.

Common Pitfalls:
Common mistakes include miscounting the days in the months before May, especially February, or forgetting whether to include or exclude the starting date when counting. Always use the correct month lengths for the specific year and reduce the total number of days modulo 7 to find the weekday shift.

Final Answer:
28th May 2006 fell on Sunday.