For the year 2019, which of the previous year's calendar can be used?
A. 2011 B. 2012 C. 2013 D. 2014
GATE 2020 · General Aptitude · Calendar · medium
Answer: The year 2013 has the same calendar as 2019. Answer: C. 2013.
Identify 2019 properties: 2019 is a non-leap year (365 days). January 1, 2019 was a Tuesday. We need another non-leap year also starting on a Tuesday.
Count odd days from 2013 to 2018 (6 years before 2019): 2013: 1, 2014: 1, 2015: 1, 2016 (leap): 2, 2017: 1, 2018: 1. Total = 1+1+1+2+1+1 = 7 = 0 mod 7.
Verify 2013 is also a non-leap year: 2013 is a non-leap year (365 days), same as 2019. Both start on Tuesday. Therefore the calendars are identical.