# Procedure to calculate the day of the week for a given date.

To calculate the day of the week for a given date, first of all we need to find out the number of odd days.

Today I thought of sharing a beautiful problem I learned in my school, though it is easy, it is tricky too. Odd Days are number of days more than the complete number of weeks in given period. Leap Year is the year which is divisible by 4. A normal year has 365 days A leap year has 366 days One normal year = 365 days = 52weeks + 1day One normal year has one odd day

One leap year = 366 days = 52weeks + 2days One leap year has two odd days

100 years = 76 ordinary years + 24 leap years = 5200 weeks + 124 days = 5217 weeks + 5 days 100 years have 5 odd days

400 years have (20+1) 0 odd days

The number of odd days and the corresponding day of the week is given below

0-Sunday 1-Monday 2-Tuesday 3-Wednesday 4-Thursday 5-Friday 6-Saturday

So by finding out the number of odd days you can find out the day of the week. I hope this procedure Will be helpful in solving math problems in exams.

Thanks.

### years divisible by 100

There is an exception to ”years divisible by 4 being leap years”: If a year is divisible by 100 (such years are divisible by 4), such a year is a leap year ONLY IF it is also divisible by 400. For example, 2000 was a leap year, but 1900 was not. Shockley’s ”Introduction to Number Theory” contains a ”day of the week” formula that includes the above fact.