Reasoning Ability - Calendar Problems
What day of the week was 31st December 1900?
What day of the week was 31st December 1900?
medium Q4 of 15
Step-by-Step Solution
Step 1: Inputs
q = 31,m = 12,year = 1900.Step 2: Compute K and J
K = 1900 % 100 = 0,J = floor(1900 / 100) = 19.Step 3: Evaluate components
floor(13*(12+1)/5) = floor(169/5) = 33;floor(K/4)=0;floor(J/4)=4;5*J = 95.
Sum:h = (31 + 33 + 0 + 0 + 4 + 95) = 163→163 mod 7 = 2.Step 4: Map result to weekday
Zeller mapping:0 = Saturday, 1 = Sunday, 2 = Monday, 3 = Tuesday, 4 = Wednesday, 5 = Thursday, 6 = Friday. Soh = 2→ Monday.Final Answer:
Monday → Option DQuick Check:
Zeller result (h = 2) ⇒ Monday; cross-check with historical calendar references confirms 31-Dec-1900 = Monday ✅
Quick Trick: Remember century-year 1900 is not a leap year — affects K/J contributions.
Common Mistakes:
MISTAKES- Treating 1900 as leap (it is not, since not divisible by 400).
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