## Calender

### Suggested Lessons

1. Odd Days: We are supposed to find the day of the week on a given date. For this, we use the concept of 'odd days'.   In a given period, the number of days more than the complete weeks are called odd days. 2. Leap Year: (i). Every year divisible by 4 is a leap year, if it is not a century.   (ii). Every  century is a leap year and no other century is a leap year. Note: A leap year has 366 days. Examples: i. Each of the years 1948, 2004, 1676 etc. is a leap year. ii. Each of the years 400, 800, 1200, 1600, 2000 etc. is a leap year. iii. None of the years 2001, 2002, 2003, 2005, 1800, 2100 is a leap year.   3. Ordinary Year:’   The year which is not a leap year is called an ordinary years. An ordinary year has 365 days. 4. Counting of Odd Days: i. 1 ordinary year = 365 days = (52 weeks + 1 day.) ∴   1 ordinary year has 1 odd day. ii. 1 leap year = 366 days = (52 weeks + 2 days) ∴    1 leap year has 2 odd days. iii. 100 years = 76 ordinary years + 24 leap years = (76 x 1 + 24 x 2) odd days = 124 odd days. = (17 weeks + days) 5 odd days. ∴  Number of odd days in 100 years = 5. Number of odd days in 200 years = (5 x 2) 3 odd days. Number of odd days in 300 years = (5 x 3) 1 odd day. Number of odd days in 400 years = (5 x 4 + 1) 0 odd day. Similarly, each one of 800 years, 1200 years, 1600 years, 2000 years etc. has 0 odd days. 5. Day of the Week Related to Odd Days:
No. of days:0123456
Day:Sun.Mon.Tues.Wed.Thurs.Fri.Sat.