Concept of Ordinary and Leap years
Ordinary Year
An ordinary year is a year which has 365 days (52 weeks + 1 odd day).
Such years are not divisible by 4, e.g. 2001, 2002, 2003, 2005, 2006, 2007, 2009, 2010 and 2011, etc.
Ordinary years in the form of century are not exactly divisible by 400, e.g. 100, 200, 500, 600, 700 and 900 etc.
Properties of Ordinary Year
In an ordinary year, the first and last days of the year are same e.g., In an ordinary year, if 1st January falls on Monday, then 31st December will also be on Monday.
In any two consecutive ordinary years, date of the next year will be one day ahead of the same date of the previous year, e.g. If 2nd August, 2010 is Tuesday, then 2nd August, 2011 will be Wednesday.
Leap Year
A leap year is a year which has 366 days (52 weeks + 2 days).
Such years are exactly divisible by 4, e.g. 2004, 2008, 2012, 2016, etc.
Leap years in the form of a century are exactly divisible by 400, e.g. 400, 800, 1200, 1600, 2000, 2400, etc.
Properties of Leap Year
- Last day of a leap year is one day ahead of the first day, e.g. in a leap year, if 1st January, 2004 falls on Monday, then 31st December, 2004 will be on Tuesday.
1st Jan 2015 – Thursday
1st Jan 2016 – Friday (2016 is a leap year)
1st Jan 2017 – Sunday
1st Jan 2018 – Monday
1st Jan 2019 – Tuesday
1st Jan 2020 - Wednesday (2020 is a leap year)
Q. Which of the following years did not have 29 days in February month?
(a) 2000 (b) 2004 (c) 1996 (d) 1966
Explanation:
A leap year is completely divisible by 4. In case of century years, only those divisible by 400 are leap years.
Among the given options, only 1966 does not get completely divided by 4. So, it is not a leap year and will have 28 days in February.
Answer: (d)
Q. If Friday is the first day of a non-leap year, what day would the last day of the year be?
(a) Friday (b) Sunday (c) Monday (d) Tuesday
Explanation:
So, if the first day is Friday, the last day will also be Friday.
Answer: (a)
Q. If in a particular year December had 9 weekend days (Saturdays and Sunday), then in that year January had how many weekends?
(a) 8 (b) 9 (c) 10 (d) None of these
Explanation:
Here we have two cases:
Case I:
If December starts with Thursday, then it will have 5 Saturdays and 4 Sundays, i.e. a total of 9 weekend days. In this case 31st December will be Saturday.
So, the 1st January of that year must have been either Saturday (For non-leap year) or Friday (For leap year).
So, January must have had 10 weekend days.
Case II:
If December starts with Sunday, then it will have 4 Saturdays and 5 Sundays, i.e. a total of 9 weekend days. In this case 31st December will be a Tuesday.
Hence, 1st January will be either Tuesday (For non-leap year) or Monday (For leap year).
So, January will have 8 weekend days.
Hence, the number of weekend days in January of that year must have been 8 or 10.
Answer: (d)
Q. Ram was born on 29th February. He celebrated his birthday falling on exactly 29th February 2008 for the fourth time. In which year he was born?
(a) 1992 (b) 2004 (c) 2000 (d) 1996
Explanation:
It's given that, Ram celebrated his birthday for the fourth time in 2008.
So, Ram must have celebrated his birthday for the third time in 2004.
So, Ram must have celebrated his birthday for the second time in 2000.
So, Ram must have celebrated his birthday for the first time in 1996.
Therefore, he was born in the year 1992.
Answer: (a)
Note: People rarely refer to the day someone was born as his "birthday". Rather, we call that “birthdate” or “the day one was born".