In the Gregorian calendar, on which day of the week did 19th April 1986 fall?

Introduction / Context:
Determining the day of the week for a past date such as 19th April 1986 is a classic calendar reasoning task. Problems like this are popular in competitive exams and help assess your comfort with date calculations and logical thinking using the rules of the Gregorian calendar.

Given Data / Assumptions:

• Date in question: 19th April 1986.
• Calendar system: Gregorian calendar.
• 1986 is not a leap year (1986 is not divisible by 4).
• Standard month lengths in 1986:
  • January: 31 days
  • February: 28 days
  • March: 31 days
  • April: 30 days

Concept / Approach:
One way to solve this is to use a known reference date whose weekday is established and then count the number of days between that reference and 19th April 1986, reducing modulo 7. Alternatively, we can employ known general results or a perpetual calendar. For explanatory purposes, we rely on the fact (verifiable using algorithms like Zeller's congruence) that 19th April 1986 fell on a Saturday.

Step-by-Step Solution:
Step 1: Recognise that 1986 is a common year with 365 days, so it does not contain a 29th February. Step 2: Using a perpetual calendar or an algorithm such as Zeller's congruence, we input the date 19-04-1986. Step 3: These standard methods process the day, month, year and century to compute the weekday index (0 through 6). Step 4: The computation shows that 19th April 1986 corresponds to index representing Saturday. Step 5: Therefore, 19th April 1986 is a Saturday.

Verification / Alternative check:
To cross-check, you can use an independent calendar tool or known date facts—for example, many sources confirm that 1st January 1986 was a Wednesday. By counting forward month by month and applying modulo 7, you can arrive at the same conclusion, though that is more tedious. In all reliable references, 19th April 1986 appears as a Saturday, confirming our answer.

Why Other Options Are Wrong:
Wednesday, Thursday, Friday or Sunday would all require a different weekday index from the one obtained via the standard calculation. If 19th April 1986 had been any of these days, it would contradict the consistent results from multiple independent calendar computations and known references.

Common Pitfalls:
The main difficulties in such problems arise when candidates try to count days manually without a structured method, leading to off-by-one errors. Misremembering leap years or month lengths can also produce incorrect results. Using a reliable algorithm or checking against trustworthy reference dates is a safer and more exam-oriented approach.

Final Answer:
19th April 1986 fell on Saturday.