The Calendar

The Calendar of Class 10

CONCEPT

We are to find the day of the week on a mentioned date. Certain concepts are defined as under.

ODD DAYS

The no. of days exceeding the complete no. of weeks in a duration is the no. of odd days during that duration.

ORDINARY YEAR

An ordinary year has 365 days.

LEAP YEAR

A leap year has 366 days. Every year which is divisible by 4 is called a leap year. For example 1200, 1600, 1992, 2004, etc. are all leap years.

The First year of every century year ending in 00's but not a multiple of 400 is not considered a leap year. For example 900,1000, 1100, 1300, 1400, 1500, 1700, 1800, 1900, 2100 are not leap years.

COUNTING OF ODD DAYS

(i) Every Ordinary year has 365 days = 52 weeks + 1 day ∴ (ordinary year has 1 odd day).

(ii) Every leap year 366 days = 52 weeks + 2 days ∴ (leap year has 2 odd days).

(iii) 100 years = 76 ordinary years + 24 leap years ( The year 100 is not a leap year)

= 76 odd days + 2 × 24 odd days = 124 odd days.

124/7 = 5 (Remainder) = 05 odd days

Similarly, 200 years = 10 odd days = 03 odd days

300 years = 15/7 = 01 odd day

400 years = 20 + (1)/7 = 0 odd day {1 is added as 400 is a leap year}

Similarly, 800, 1200, 1600, 2000, 2400 years contain 0 odd days

COUNTING OF DAYS

After counting the odd days, we find the day according to the no. of odd days → Sunday for 0 odd day, Monday for 01 odd day and so on.

In an Ordinary Year, First & last day of the year are the same.

(i) If 1 Jan is Friday than 31 Dec. will also have Friday.

(ii) For a leap year, if first day is Monday then last day will be Tuesday for the same year.

(iii) Calendar year 1 Jan to 31 Dec. Financial year 1 April to 31 March.

(iv) The day on which calendar Started i.e., 1 Jan, 001 was Monday.

(v) In a Leap year, February is of 29 days. In an ordinary year, February has 28 days

YEAR TABLE

Ordinary Year – 365 days		Leap Year – 366 days
January	31	January	31
February	28	February	29
March	31	March	31
April	30	April	30
May	31	May	31
June	30	June	30
Total	181 days	Total	182 days
July	31	July	31
August	31	August	31
September	30	September	30
October	31	October	31
November	30	November	30
December	31	December	31
Total	184 days	Total	184 days