Which day is 10th October, 2027 ?
- (a) Sunday ✓ UPSC's answer
- (b) Monday
- (c) Tuesday
- (d) Saturday
Why the answer is (a)
• 1 January 2000 was a Saturday. From 1 January 2000 to 1 January 2027 there are 27 years, of which 7 are leap years (2000, 2004, 2008, 2012, 2016, 2020, 2024), giving 27 × 365 + 7 = 9 862 days, i.e. 1 408 weeks and 6 odd days, so 1 January 2027 falls on a Friday.
• From 1 January 2027 to 10 October 2027 the intervening days are: 30 (rest of Jan) + 28 (Feb) + 31 (Mar) + 30 (Apr) + 31 (May) + 30 (Jun) + 31 (Jul) + 31 (Aug) + 30 (Sep) + 10 (Oct) = 282 days.
• 282 ÷ 7 = 40 weeks and 2 odd days, so 10 October 2027 is two days after Friday, i.e. a Sunday.
• The correct option is therefore (a) Sunday.
Why the other options are wrong
- (b) Monday
- Monday would require 3 odd days after 1 January 2027, but the count from 1 January to 10 October gives only 2 odd days (282 mod 7 = 2), landing on Sunday, not Monday.
- (c) Tuesday
- Tuesday would require 4 odd days after 1 January 2027, but the actual remainder is 2, so the day is Sunday, not Tuesday.
- (d) Saturday
- Saturday would require 0 odd days (i.e. a multiple of 7 days) after 1 January 2027, but 282 leaves a remainder of 2, so the day is Sunday, not Saturday.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2021, held on 10 October 2021. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.