Question

What was the day on 15th August, 1947?

• A. Monday
• B. Tuesday
• C. Wednesday
• D. Thursday

Hint:

Use either odd-day counting from a known date or Zeller congruence. Remember that $1900$ was not a leap year when counting weekday shifts.

Answer 1

The Correct Option is D

Concept:

• Zeller congruence gives the weekday directly from a Gregorian date.
• Its remainder $0,1,2,3,4,5,6$ represents Saturday through Friday.

Step 1: Assign the date values.
For $15$ August $1947$, use $q=15$, $m=8$, $K=47$, and $J=19$.

Step 2: Substitute in the congruence.
$h=\left(15+\left\lfloor\dfrac{13(8+1)}{5}\right\rfloor+47+\left\lfloor\dfrac{47}{4}\right\rfloor+\left\lfloor\dfrac{19}{4}\right\rfloor+5(19)\right)\bmod7$.
$h=(15+23+47+11+4+95)\bmod7=195\bmod7=6$.

Step 3: Decode the remainder.
A remainder of $6$ denotes Friday.

Final Answer: Friday