Calendars: Odd Days & Day of Week

A comprehensive practice drill on Calendar reasoning problems frequently featured in Kerala PSC exams. It covers leap year determination (including century rules), calculating odd days across years, finding days of the week after a given duration, identifying century last days, and calendar repetition cycles.

Study Scope

• Leap Year Rules: Divisible by $$4$$, century years divisible by $$400$$
• Odd Days Concept: $$1$$ odd day in an ordinary year ($$365$$ days), $$2$$ odd days in a leap year ($$366$$ days)
• Centuries Odd Days: $$100$$ yrs ($$5$$ odd days), $$200$$ yrs ($$3$$), $$300$$ yrs ($$1$$), $$400$$ yrs ($$0$$)
• Calendar Repetition: Leap years repeat in $$28$$ years; leap+1 in $$6$$ years; leap+2 and leap+3 in $$11$$ years
• Historical Dates: Determining day of the week for landmark dates (e.g. 15 Aug 1947, 26 Jan 1950)

Tested Competencies

• Instantly determine whether any given year or century is a leap year
• Calculate the day of the week for future and past dates using odd days
• Solve calendar repetition and day-gap problems without reference charts