In a calendar based aptitude question, what day of the week was 15 August 1947, the historic date of Indian independence?

Introduction / Context:
This question tests your understanding of calendar calculations and day of the week determination for a given historical date. Dates such as 15 August 1947, the date of Indian independence, are often used in competitive exams to check whether you know how to work with the Gregorian calendar or whether you know the result as a standard fact.

Given Data / Assumptions:
- We are working with the standard Gregorian calendar.
- The date of interest is 15 August 1947.
- We must determine the day of the week on this date.
- No additional reference date is explicitly given in the question, so you can either use a known reference or a standard counting method such as odd days or Zellers congruence.

Concept / Approach:
There are two main ways to handle this problem in an exam:
1. Treat it as a fact: 15 August 1947 is widely remembered as a Friday in the Gregorian calendar.
2. Use calendar arithmetic: pick a known reference date and count the total number of days between that date and 15 August 1947, reduce that count modulo 7 to get the number of odd days, and then shift the weekday accordingly. In most exams, either method is acceptable, but knowing the fact saves time.

Step-by-Step Solution:
Step 1: Recognise that 15 August 1947 is the Indian independence day and is commonly recorded as a Friday.Step 2: If you want to verify, choose a convenient reference date whose weekday you know exactly, such as 1 January 1900 or 1 January 2000, and use a reliable day counting method.Step 3: Count complete years between the reference year and 1947, separating leap years and ordinary years, and convert the excess days into odd days.Step 4: Add the days from the start of 1947 up to 15 August (including all months January to July and 15 days of August) and again reduce modulo 7.Step 5: Combine the odd days from the years and the days in 1947, and shift the weekday of the reference date accordingly.Step 6: This systematic calculation confirms that the weekday is Friday.

Verification / Alternative check:
Because this is a famous date, you can cross check it mentally by recalling that celebrations and historical records consistently mention that independence was declared shortly after midnight going into Friday. In many calendars and history books, 15 August 1947 is explicitly labelled as a Friday, so the computed result matches the established historical fact.

Why Other Options Are Wrong:
Saturday, Sunday, Thursday and Monday are all one or more days shifted away from the correct weekday. If you perform the odd day calculation carefully or consult an accurate calendar, none of these alternatives align with 15 August 1947. Only Friday is compatible with both historical records and proper calendar arithmetic.

Common Pitfalls:
Typical mistakes include miscounting leap years, forgetting that century years are leap years only if divisible by 400, or adding an extra day for February in a non leap year. Another common issue is starting from an incorrect reference date. To avoid such errors, always be systematic in counting years and days, and when in doubt, rely on well known historical dates like this one as memorised facts.

Final Answer:
15 August 1947 fell on a Friday.