This is one of the brain improvement which you can use to amuse your friends! Learning the calendar means to know what day it is every time you see a date. When your friends ask you what day is it on 1 January 1987, you'll be able to tell them that it's Thursday!
Other examples:
3 March 1865 : Friday
27 October 2066: Wednesday
Your friends will definitely say, how did you do that?!
It's easy, but it's also difficult. I mean, you have to memorize the codes first, then you can amuse your friends! There are some codes to memorize.
For the explanation, I will use the date 29 May 2057
There are 3 things you get from a date: day, month, year, and century. Thus, there are 4 kinds of codes:
- Day Code
The day code is easy, in fact, you don't have to memorize anything! We are working with the basis 7 here, so subtract the day number by 7 until it can't be subtracted again.
Example: 29 you get from 29 May 2057, subtracted by 7 for 4 times leaves you with 1. So here, the code is 1. - Month Code
Here, you have to memorise the code for each month:- January : 1
- February : 4
- March : 4
- April : 0
- May : 2
- June : 5
- July : 0
- August : 3
- September: 6
- October : 1
- November : 4
- December : 6
- Year Code
Year code is the most important part of this method. You have to memorize the code for each year, to make it easier, I divide them into 7 categories:
I will present them just straight to the year, for example: 57, 68, 99
Year code: 0
The year: 00, 06, 17, 23, 28, 34, 45, 51, 56, 62, 73, 79, 84, 90
Year code: 1
The year:01, 07, 12, 18, 29, 35, 40, 46, 57, 63, 68, 74, 85, 91, 96
Year code: 2
The year: 02, 13, 19, 24, 30, 41, 47, 52, 58, 69, 75, 80, 86, 97
Year code: 3
The year: 03, 08, 14, 25, 31, 36, 42, 53, 59, 64, 70, 81, 87, 92, 98
Year code: 4
The year: 09, 15, 20, 26, 37, 43, 48, 54, 65, 71, 76, 82, 93, 99
Year code: 5
The year: 04, 10, 21, 27, 32, 38, 49, 55, 60, 66, 77, 83, 88, 94
Year code: 6
The year: 05, 11, 16, 22, 33, 39, 44, 50, 61, 67, 72, 78, 89, 95
For this example: 2057 means that the number is 57 with the code 1. - Century Code
For the century code, it has a series: 6, 4, 2, 0, ...
Starting from 1600s : 6
1700s : 4
1800s : 2
1900s : 0
2000s: 6
and so on...
For this example: 2057 means that it's in the 2000s with the code 6.
Day code: 1
Month code: 2
Year code: 1
Century code: 6
Sum the codes you have : 1 + 2 + 1 + 6 = 10
Again, we are working with the basis 7, so subtract all 7s, that leaves you with 3.
Translation code:
1 : Sunday
2 : Monday
3 : Tuesday
4 : Wednesday
5 : Thursday
6 : Friday
0 : Saturday
Thus, 29 May 2057 falls on Tuesday!
Leap Year:
For leap years, subtract 1 from the total.
IMPORTANT : Do this only when the date is between 1 January and 29 February!
Example: 24 January 1912
Day code : 3
Month code : 1
Year code : 1
Century code : 0
TOTAL: 5
It is a leap year. Thus, subtract 1:
The total is 4, means that it's Wednesday!
I think that's all, just memorize those codes and you'll be ready to amuse your friends in no time!
Good luck!