Find the day of the week for 1st January 1800 using Zeller’s formula.

medium Q7 of 15

Reasoning Ability - Calendar Problems

AWednesday

BThursday

CFriday

DSaturday

Step-by-Step Solution

Step 1: Jan treated as month 13 of previous year
Use q = 1, m = 13, year = 1799.
Step 2: Compute K and J
K = 1799 % 100 = 99, J = floor(1799 / 100) = 17.
Step 3: Evaluate components
floor(13*(13+1)/5) = 36;
floor(K/4)=24;
floor(J/4)=4;
5*J = 85.
Sum: h = (1 + 36 + 99 + 24 + 4 + 85) = 249 → 249 mod 7 = 4.
Step 4: Map result to weekday
4 → Wednesday. So 1-Jan-1800 = Wednesday.
Final Answer:
Wednesday → Option A
Quick Check:
Historical calendars confirm 1-Jan-1800 = Wednesday ✅

Quick Trick: When working with old centuries, compute J carefully (here J=17).

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