How to determine what day you were born?

Calendar formula

here is the mathematical formula

d = (k + m - 2c + y + ydiv4 + cdiv4) mod 7, this formula is only applicable from March to December(both leap years and non leap years)

d = (k + m - 2c + y - 1 + ydiv4 + cdiv4) mod 7, this formula is only applicable from January and February(non leap years)

d = (k + m - 2c + y - 2 + ydiv4 + cdiv4) mod 7, this formula is only applicable from January and February(leap years)

legend:
d = day
k = date, 1,2...31
m = month
c = century, 18,19,20...
y = year, 85,86,98,08,...

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

day: you will encounter negative days if you use the long method
0 = Sunday
-1 = Saturday
-2 = Friday
-3 = Thursday
-4 = Wednesday
-5 = Tuesday
-6 = Monday


month:
0 = January
3 = February
2 = March
5 = April
0 = May
3 = June
5 = July
1 = August
4 = September
6 = October
2 = November
4 = December


Leap Year Trivia
Some exceptions to this rule are required since the duration of a solar year is slightly less than 365.25 days. Years that are evenly divisible by 100 are not leap years, unless they are also evenly divisible by 400, in which case they are leap years.[ For example, 1600 and 2000 were leap years, but 1700, 1800 and 1900 were not in the 1582 papal bull (the 1750 British Calendar Act ignores 1700). Similarly, 2100, 2200, 2300, 2500, 2600, 2700, 2900, and 3000 will not be leap years, but 2400 and 2800 will be. By this rule, the average number of days per year will be 365 + 1/4 − 1/100 + 1/400 = 365.2425, which is 365 days, 5 hours, 49 minutes, and 12 seconds.

Interesting website:

http://www.dayofbirth.co.uk/


visit that website if you don't care about math or you're not good at it

if you find this video boring, haha, The reason I created this video is for the people who can comprehend math!!!

Category:

Education

Tags:

• calendar
• mathematics
• formula
• equation

[marydenay82]

what is module 7?

[underclassdamnriot]

it is read as MODULO 7, It is a DIVISION but you will only get the remainder. If the divisor is 7, the only range of possible remainders are (0 to 6). if MODULO 5, (0 to 4), if modulo 2 (0 & 1) always minus 1 to the highest range!!! get it, for example 21 mod 7 the quotient is 3, the remainder is 0 so 21 mod 7 = 0. Get it???

[underclassdamnriot]

^i am also confused at first when i am solving this but i got used to it so it's easy already. Why March is 2? look at the description, march's value is 2. 1990,19 is century here and 90 is year. k = 15. Simple as that then solve

[naruto64kun]

holy shit dude thanks a lot and i finally got it after going trough it over 10 times its tuesday!!!! even my mom confirmed it!!!!!!!!  your awesome

[underclassdamnriot]

ok thanks for appreciating, i created a part 2 video for it, please watch, for example, your birtday is leap year, you either born on january or february, you will use this formula

d = (k + m - 2c + y - 2 + ydiv4 + cdiv4) mod 7

[naruto64kun]

whoa i think this works but its to hard for me to do

[underclassdamnriot]

so naruto64kun, i will explain it to you!!! for example your birthday is march 15, 1990, look at the description. March is 2, k = 15, y = 90, c = century then compute using the formula # 1 and substitute these values to the variables. Since your month is march. Div is a division, when you get the quotient, you will discard the decimal part. Mod is modulo aka remainder when you divide 2 numbers.

[naruto64kun]

cha...i spent like 20 mins trying to figure it out but im getting confused with the amount of years and skip years....some years have more days than others!!!