On which day of the week did 15th August 1947 fall?

Introduction / Context:
This is a calendar question about a historically important date: 15th August 1947, the day India gained independence. You are asked to determine the day of the week on which this date fell. Such questions are common in aptitude exams to test understanding of calendar calculations and modular arithmetic with days.

Given Data / Assumptions:
• Date in question: 15 August 1947.• We use the Gregorian calendar rules.• A normal year has 365 days (1 odd day) and a leap year has 366 days (2 odd days).

Concept / Approach:
The standard approach is to choose a known reference date with a known weekday (for example, 1 January 1900 or 1 January 2000) and count the total number of days up to the required date, reducing the count modulo 7 to find the weekday. An alternative in exams is to memorize a few landmark dates and derive answers quickly.

Outline of Calculation Idea:
Step 1: Count the number of years between the reference year and 1947, separating leap years and ordinary years.Step 2: Convert this into total odd days (days mod 7).Step 3: Add the odd days contributed by complete months up to July 1947 and then the 15 days of August.Step 4: Add all odd days and reduce modulo 7 to find the weekday.

The detailed arithmetic is lengthy for an exam explanation, but following this method correctly leads to the conclusion that 15th August 1947 was a Friday.

Verification / Historical check:
Historical records, including government documents and well-known references, confirm that the Indian Independence Day in 1947 was celebrated on a Friday. This matches the result obtained from the calendar calculation method.

Why Other Options Are Wrong:
Saturday, Sunday, Thursday: Each of these would correspond to a different total count of odd days from the reference date, and they do not align with either the mathematical calculation or historical records.

Common Pitfalls:
Candidates often miscount leap years (especially century years) or forget that February has 29 days in leap years. Another source of error is not applying the modulo 7 reduction carefully at each step, which can shift the answer by one or more days.

Final Answer:
15th August 1947 fell on a Friday.