PPT: Calendars | CSAT Preparation - UPSC PDF Download

 Page 1


Calendars
Page 2


Calendars
Introduction to Calendars
Definition
A system organizing days, weeks, and months for various purposes (e.g., social, 
administrative).
Importance
Crucial for logical reasoning . Involves complex logical analysis and math skills. Typically 234 
questions in exams.
Page 3


Calendars
Introduction to Calendars
Definition
A system organizing days, weeks, and months for various purposes (e.g., social, 
administrative).
Importance
Crucial for logical reasoning . Involves complex logical analysis and math skills. Typically 234 
questions in exams.
Basic Structure of a Calendar
Ordinary Year
365 days = 52 weeks + 1 
odd day.
Leap Year
366 days = 52 weeks + 2 
odd days.
Odd Days
Extra days beyond 
complete weeks, key to 
day calculations.
Page 4


Calendars
Introduction to Calendars
Definition
A system organizing days, weeks, and months for various purposes (e.g., social, 
administrative).
Importance
Crucial for logical reasoning . Involves complex logical analysis and math skills. Typically 234 
questions in exams.
Basic Structure of a Calendar
Ordinary Year
365 days = 52 weeks + 1 
odd day.
Leap Year
366 days = 52 weeks + 2 
odd days.
Odd Days
Extra days beyond 
complete weeks, key to 
day calculations.
Concept of Odd Days
Odd Days in Months
31 days = 3 odd days (e.g., Jan, Mar). 
30 days = 2 odd days (e.g., Apr, Jun). 
Feb: 0 odd days (ordinary year), 1 odd day 
(leap year).
Odd Days in Years
Ordinary year: 1 odd day. Leap year: 2 odd 
days.
Odd Days in Centuries
100 years: 5 odd days. 200 years: 3 odd days. 
300 years: 1 odd day. 400 years: 0 odd days 
(calendar repeats).
F o r mu la : Odd days = Remainder of (T otal 
days/7).
Month Days Odd Days 
(Ordinary)
Odd Days (Leap)
January 31 3 3
February 28/29 0 1
March 31 3 3
April 30 2 2
May 31 3 3
June 30 2 2
July 31 3 3
August 31 3 3
September 30 2 2
October 31 3 3
November 30 2 2
December 31 3 3
Page 5


Calendars
Introduction to Calendars
Definition
A system organizing days, weeks, and months for various purposes (e.g., social, 
administrative).
Importance
Crucial for logical reasoning . Involves complex logical analysis and math skills. Typically 234 
questions in exams.
Basic Structure of a Calendar
Ordinary Year
365 days = 52 weeks + 1 
odd day.
Leap Year
366 days = 52 weeks + 2 
odd days.
Odd Days
Extra days beyond 
complete weeks, key to 
day calculations.
Concept of Odd Days
Odd Days in Months
31 days = 3 odd days (e.g., Jan, Mar). 
30 days = 2 odd days (e.g., Apr, Jun). 
Feb: 0 odd days (ordinary year), 1 odd day 
(leap year).
Odd Days in Years
Ordinary year: 1 odd day. Leap year: 2 odd 
days.
Odd Days in Centuries
100 years: 5 odd days. 200 years: 3 odd days. 
300 years: 1 odd day. 400 years: 0 odd days 
(calendar repeats).
F o r mu la : Odd days = Remainder of (T otal 
days/7).
Month Days Odd Days 
(Ordinary)
Odd Days (Leap)
January 31 3 3
February 28/29 0 1
March 31 3 3
April 30 2 2
May 31 3 3
June 30 2 2
July 31 3 3
August 31 3 3
September 30 2 2
October 31 3 3
November 30 2 2
December 31 3 3
Leap Year Evaluation
Rule
Divisible by 4 = Leap year. Century years: Must be divisible by 400 (not just 100).
Examples
2016: Leap year (divisible by 4). 1900: Not a leap year (divisible by 100, not 400). 2000: 
Leap year (divisible by 400).
Formula
Leap year if Remainder of (year/4 = 0) AND Remainder of year/100 is not = 0 OR 
Remainder of year/400 = 0.