Minimalist IAS
CSAT 2024 paper

UPSC CSE CSAT 2024 · Question 38 · Puzzles, arrangements & general mental ability

The calendar for the year 2025 is same for

The calendar for the year 2025 is same for

Answer & explanation

Answer: (c) 2031

2025 is an ordinary year. Adding odd days year by year (2025: 1, 2026: 1, 2027: 1, 2028: 2, 2029: 1, 2030: 1) reaches 7 at the end of 2030, so 2031 begins on the same weekday. It is also an ordinary year, so its calendar matches 2025.

  1. An ordinary year has 1 odd day; a leap year has 2.
  2. Odd days from the start of 2025: 1 + 1 + 1 + 2 (2028 is a leap year) + 1 + 1 = 7, a whole number of weeks, by the end of 2030.
  3. So 1st January 2031 falls on the same weekday as 1st January 2025 (a Wednesday).
  4. 2031, like 2025, is not a leap year, so the whole calendar repeats.
  5. Check: by the start of 2029 only 5 odd days have gathered, and by the start of 2033 there are 10, which leaves 3; neither gives a match.

Remember · For an ordinary year, add odd days until the total is a multiple of 7, then confirm the target year is also ordinary.

Question and answer: UPSC's official GS Paper II (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·

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