Calendar calculation – Suresh was born on 4 October 1999. Shashikanth was born 6 days earlier. Given that Independence Day (15 August 1999) fell on a Sunday, determine the weekday of Shashikanth’s birth.

Introduction / Context:
This is a classic calendar arithmetic problem: translate a known weekday for a reference date into the weekday for a target date using day differences modulo 7.

Given Data / Assumptions:

• 15 Aug 1999 (Independence Day) = Sunday.
• Suresh’s DOB = 4 Oct 1999.
• Shashikanth’s DOB = 6 days before 4 Oct 1999 = 28 Sep 1999.

Concept / Approach:
Compute the difference in days from 15 Aug 1999 (Sunday) to 28 Sep 1999; reduce modulo 7; apply the shift to Sunday to find the target weekday.

Step-by-Step Solution:
From 15 Aug to 31 Aug = 16 days.From 1 Sep to 28 Sep = 28 days.Total = 16 + 28 = 44 days.44 mod 7 = 2 (since 42 is a multiple of 7).Sunday + 2 days = Tuesday.

Verification / Alternative check:
Counting by weeks: 6 weeks (42 days) after Sunday is Sunday; add 2 more days to reach Tuesday, matching the result.

Why Other Options Are Wrong:
Monday or Wednesday are ±1 from the correct 2-day shift; Sunday implies zero shift, which contradicts the 44-day gap.

Common Pitfalls:
Forgetting that Aug has 31 days, or miscounting inclusive/exclusive bounds; using 43 or 45 instead of 44 leads to a one-day error.

Final Answer:
Tuesday