Which date of June 2099 among the following is Sunday?
- (a) 4
- (b) 5
- (c) 6
- (d) 7 ✓ UPSC's answer
Why the answer is (d)
• Use Zeller's congruence for the Gregorian date 7 June 2099, with q=7, m=6, K=99, and J=20.
• Compute floor(13(m+1)/5)=18, floor(K/4)=24, floor(J/4)=5, and 5J=100.
• Add the terms: 7 + 18 + 99 + 24 + 5 + 100 = 253.
• Divide 253 by 7: 253 = 7 × 36 + 1, and remainder 1 means Sunday.
• Hence 7 June 2099 is Sunday, so option (d) follows.
Why the other options are wrong
- (a) 4
- Option (a) is wrong because 4 June 2099 is Thursday.
- (b) 5
- Option (b) is wrong because 5 June 2099 is Friday.
- (c) 6
- Option (c) is wrong because 6 June 2099 is Saturday.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.