Calculating calendar dates.............improve calculation speed also..............

[sunish]

hello all!!!!!!!

the questions of calculating calendar dates usually comes in CAT etc..........
many of you may know many tricks of calculating calendar dates and those may be easy than the following method but this method also buits up the calculation speed as a whole...........
u may do one thing: now as u r sitting in front of the pc , click on the time display of the taskbar............a window will open in which there is diplay of a watch n a calendar.............. while seeing the watch and stare at any date in the calendar and apply the following method to arive at its day..............religiuosly follow this and u may increase ur speed of calculation.............change the calendar and utilise the method...........i have devised this method to improve my speed ( the method of calculation is not mine but theWCT watch,calendat taskbar method is mine)............

the method is as follows:

What day of the week will May 12, 2034 be? What day of the week was May 12, 1298? Here's a neat algorithm that will tell you:


(Note: all divisions, except where noted otherwise, are integer divisions, in which remainders are discarded.)

First figure out the values for a, y, and m -- variables to be plugged into a formula.

a = (14 - month)/12 (month = # of month, 1 for Jan, 2 for Feb, etc)

y = year - a (year = the 4 digit year)

m = month + 12a - 2

Next, plug the values of y and m into the following formula to calculate the day:

d = (day + y + y/4 - y/100 + y/400 + 31m/12) mod 7

(Note: mod 7 means "modulo division." That is, take the remainder instead of the quotient as your answer. For example, 20 mod 3 = 2, because the remainder is 2.)

The answer you get for d will correspond to a day of the week as such:

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

Here's an example.
What day of the week will April 5, 2020 fall on?

First figure out a, y, and m:

a = (14 - 4)/12 = 0 (remember, it's integer division so remainders are discarded. 4 represents the month of April since it's the fourth month of the year.)

y = 2020 - 0 = 2020

m = 4 + 12(0) - 2 = 2

Now plug y and m into the d formula to calculate the day:

d = (5 + 2020 + 2020/4 - 2020/100 + 2020/400 + 31(2)/12) mod 7
d = (5 + 2020 + 505 - 20 + 5 + 5) mod 7
d = 2520 mod 7
d = 0 (2520/7 = 360 with a remainder of 0)

Recall from above that 0 = Sunday. So April 5, 2020 will be a Sunday.

Cool, huh? Remember, you can do this for dates in the past as well.

(COURTESY CURIOUS MATH)

do tell me abt ur results

[manjumba]

:P THANK U
IT HELPED A LOT

MANJU

[ILLUMINATUS]

yeah.... real good work dude... do keep posting such tips n tricks
blitzkrieg

[newguy]

This is really good !

Just one question....

In some question, they give some hypothetical scenario..such as if 1st march is a sunday then what will be 7th dec of next year.....in such question, do you first apply this method to find what 1st march is ...and then see the offset and then go on to 7th dec of next year..I guess I am confusing you..just tell me what you do with such hypothetical cases where year is not given...only some initial condition is given...

[Jackal]

i guess it works somethin like.. if x date of x month is some day say like.. sunday then x date of the x month of the next yr will b monday.. thz cuz when u divivde 365 by 52 u get 1 remainder.. so 4 ordinary yr u add a day n 4 leap yrs 2 days.. n then in the same way reach to the particular date they have asked by using the same thing in months.. (ie 4 30 day month add 2 days 4 a 31 day month add 3 days etc)

cheers

[siddharthaduggirala]

Originally Posted by sunish

hello all!!!!!!!

the questions of calculating calendar dates usually comes in CAT etc..........
many of you may know many tricks of calculating calendar dates and those may be easy than the following method but this method also buits up the calculation speed as a whole...........
u may do one thing: now as u r sitting in front of the pc , click on the time display of the taskbar............a window will open in which there is diplay of a watch n a calendar.............. while seeing the watch and stare at any date in the calendar and apply the following method to arive at its day..............religiuosly follow this and u may increase ur speed of calculation.............change the calendar and utilise the method...........i have devised this method to improve my speed ( the method of calculation is not mine but theWCT watch,calendat taskbar method is mine)............

the method is as follows:

What day of the week will May 12, 2034 be? What day of the week was May 12, 1298? Here's a neat algorithm that will tell you:


(Note: all divisions, except where noted otherwise, are integer divisions, in which remainders are discarded.)

First figure out the values for a, y, and m -- variables to be plugged into a formula.

a = (14 - month)/12 (month = # of month, 1 for Jan, 2 for Feb, etc)

y = year - a (year = the 4 digit year)

m = month + 12a - 2

Next, plug the values of y and m into the following formula to calculate the day:

d = (day + y + y/4 - y/100 + y/400 + 31m/12) mod 7

(Note: mod 7 means "modulo division." That is, take the remainder instead of the quotient as your answer. For example, 20 mod 3 = 2, because the remainder is 2.)

The answer you get for d will correspond to a day of the week as such:

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

Here's an example.
What day of the week will April 5, 2020 fall on?

First figure out a, y, and m:

a = (14 - 4)/12 = 0 (remember, it's integer division so remainders are discarded. 4 represents the month of April since it's the fourth month of the year.)

y = 2020 - 0 = 2020

m = 4 + 12(0) - 2 = 2

Now plug y and m into the d formula to calculate the day:

d = (5 + 2020 + 2020/4 - 2020/100 + 2020/400 + 31(2)/12) mod 7
d = (5 + 2020 + 505 - 20 + 5 + 5) mod 7
d = 2520 mod 7
d = 0 (2520/7 = 360 with a remainder of 0)

Recall from above that 0 = Sunday. So April 5, 2020 will be a Sunday.

Cool, huh? Remember, you can do this for dates in the past as well.

(COURTESY CURIOUS MATH)

do tell me abt ur results

This is just awesome!! Can u come up with more stuff like this

[gpta_varun]

Hi ... Great concept ......

But i for some reason not getting the answer for 15 the sep 1698 .

Can anyone hlp me out .





thnx