1. Odd Days: The number of days more than the complete weeks for a given period called odd days.
2. Ordinary Year: An ordinary year has 365 days and an ordinary year is not a leap year.
3. Leap Year:
(a) Any year (except a century) which is divisible by 4 is a leap year.
(b) However, every 4th century is a leap year, ie, a century is a leap year when it is divisible by 400.
(c) A leap year has 366 days.
Examples of Leap Year 1924, 1908, 1944, 2008, 1684, etc., are all leap years.
400, 800, 1200, 1600, 2000, etc., are all leap years.