main law

we are planning to calculate Einstein date of birth (14 march, 1897)

(century code + year code + month code + day - leap year) % 7

0 - sun
1 - mon
2 - tue
3 - wed
4 - thu
5 - fri
6 - sat

century code of Gregorian (4206420)

1700 - 4
1800 - 2
1900 - 0
2000 - 6
2100 - 4
2200 - 2
2200 - 0

`1897` belongs to 1800 century so year code is `2`

year code

law of the year code


(YY + (YY / 4)) % 7

here YY is last 2 digit of the year
in case of 1897, YY is 97
since (97 + (97 / 4)) % 7) is 2, So year code is 2

month code `033614625035`

January - 0
February - 3
march - 3
April - 6
may - 1
June - 4
July - 6
august - 2
September - 5
October - 0
November - 3
December - 5

Since Einstein born in march so month code is 3

leapyear code

YYYY % 4 == 0 ? 'leapyear' : 'not leapyear' ;
&&
YYYY % 100 != 0 || YYYY % 400 == 0 ? 'leapyear' : 'not leapyear'

Since 1897 is not divisible by 4 so its not leap year. So leap year code 0

final calculation

Einstein date of birth : 14 march, 1897
century code for 1800 = 2
year code (97 + (97 / 4)) % 7 = 2
month code march = 3
day of the month = 14
leap year code = 0
(century code + year code + month code + day - leap year) % 7
(2 + 2 + 3 + 14 - 0) % 7
21 % 7 = 0
0 means Sunday