Calendar

INTRODUCTION:
There are two types of years, such as: (i) Ordinary year. (ii) Leap year. Ordinary year: It consists of 365 days. In terms of weeks, it consists of 52 weeks and the remainder is 1 which is 1 odd day.
Leap year: The non-century years which are divisible by 4 and the century years divisible by 400 are leap years. It contains 52 weeks and 2 odd days.

The number of odd days in 100 years are 5.
The number of odd days in 200 years are 3.
The number of odd days in 300 years are 1.
The number of odd days in 400 years are 0.

METHOD TO FIND OUT DAY:
To find out the day, we have to find out the number of odd days according to the following 4 steps:
Step I: Number of odd days in the passed century.
Step II: Number of odd days in the passed year.
Step III: Number of odd days in the continuing year in terms of month wise..
Step IV: Number of odd days in the continuing month till the exact day.

Finally n if the number of odd day is 1, it is Monday.
if the number of odd day is 2, it is Tuesday.
if the number of odd day is 3, it is Wednesday.
if the number of odd day is 4, it is Thursday.
if the number of odd day is 5, it is Friday.
if the number of odd day is 6, it is Saturday.
if the number of odd day is 0, it is Sunday.

Example

Find out the day on 9th June 1971.
Solution: In 1900, the number of odd day is 1.
In70 years, the number of odd days are as follows:
If all 70 years are ordinary years, the number of odd days are 70, but out of 70 years 17 are leap years in which 17 odd days more i.e. 87 odd days and finally 3 odd days.
According to month wise Jan 3, Feb 0, Mar 3, Apr 2, May 3, so finally it is 4.
According to date wise, the number of odd day is 2.
Finally, the number of odd day is 3 that’s why the day is Wednesday.

If today is Tuesday, then after 65 days it will be which day?
Solution: nIn 65 days, there are9 weeks and 2 odd days
So the day will be 2 days ahead of Tuesday i.e. Thursday.