Aptitude - Calendar - Discussion

Use doomsday algorithm :

Remember that last day of feb , 4th april, 6th july , 8th august , 10th october and 12th december will have the same day of week which is known as doomsday and we need to calculate it in the following way :

For 1900-1999 always take the anchor day as wednesday.
For 2000-2099 always take base anchor day as tuesday.

So now formula for calculating the doomsday:

Doomsday = anchor(wed for 1900-99 tue for 2000-2099) + Y/12(ignore decimal) + remainder(Y/12) + {remainder(Y/12)/4}.

Take only last two digits of the Year.

Based on the formula we have for 17th june 1998 we have:

Doomsday = wednesday + 98/12 + Remainder(98/12) + Remainder(98/12)/4.

Wednesday + 8 + 2 + 2/4.
Wednesday + 8 + 2 + 0 = wednesday + 10 = saturday.

So from the above list mentioned for the nearest doomsday we can see that 6th june is the nearest doomsday.

So 6th june will have the day Saturday.

17th june - wednesday.

Number of odd days in 97 years (24 x 2 + 73) = 121 = 2 odd days.

Can't understand this part. Can anybody explain me this part ?

How we got 24 leap year in 100 year.

It should be 100/4 = 25.

Why not 25? but 24.

Why 400 years have 0 odd day?

To find out any day of any year of date we have to go through a formula.

Always remember Code:

Jan Feb Mar Apr May June July Aug Sep Oct Nov Dec
31 (28/29) 31 30 31 30 31 31 30 31 30 31
3 (0/1) 3 2 3 2 3 3 2 3 2 3

So now today is 17/05/2014 is Saturday.(today's date)
Calculate 17/05/1998.

Now leap year(the year which is divisible by 4 or 400) coming between 1998 and 2014 is 2000,2004,2018,2012 means 4.

And year gap between 1998 to 2014 is 16.

Now add 16 to 4 and then divide with 7(days in a week)
the result gives (16+4)/7= 6

So if today is Saturday then 17/05/1998 will be Saturday - 6 = Sunday.(since we are coming to back year so we should differentiate)
Now calculate days between 17/05/1998 to 17/06/1998 is 31 day.

Now divide 7 in 31, result is 3

So if 17/05/1998 is Sunday then 17/06/1998 will be Sunday + 3= Wednesday.(Since we are going forward year we should add)

Solution:

First we calculate upto 1997.
1998 = 1600+300+97.

For 1600 0odd days because 1600 is divisible by 4 so it is 0.
For 300 is 1 odd days.
For 97 we have 24 leap year and 73 ordinary year.
Calculate if leap year*2 so 24*2 = 48+73.
=121.

While dividing 121 by 7 we get remainder as 2 that is 2 odd days.
Still we have to calculate from jan 1998 to 17th june 1998 we have 168 days if We divided by 7 remainder is zero.
Totally we have 3 odd days.

Sun Mon Tue Wed Thu Fri Sat
0 1 2 3 4 5 6
So answer is wed.

How to calculate leap year and ordinary year between 200 years?

First divide that no by 4.
200/4 = 50 is the leap year.
And 200-50 = 150 is the ordinary year.

Friends it's so simple, Remember only code:

Year Code:

1600-1699 = 6.
1700-1799 = 4.
1800-1899 = 2.
1900-1999 = 0.
2000-2099 = 6.

Month Code:

Jan = 0
Feb = 3
Mar = 3
April = 6
May = 1
June = 4
July = 6
Aug = 2
Sep = 5
Oct = 0
Nov = 3
Dec = 5

Day Code:

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

Steps to solve:

What was day on 17/8/1998 ?

Step:1 (add day + last two digit of years).

(17+98=115).

Step:2 (divide last two digit of years by 4).

98/4 == 24.

Step:3 (add code value)

115
+24
+04 --- month code.
+00 --- year code.
-----
143.

Step: 4 (divide result step 3 by 7).

143/7 = 3.

Step:5 (match with day code).

3 === Wednesday.

Please any one explain how to find 11th oct 1993 - day?

But above explained rules are not giving exact day what it is.