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The Magic Cafe Forum Index :: Magical equations :: Equation for the day of the week (0 Likes) Printer Friendly Version

Good to here.
Fedora
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Arizona, usa
760 Posts

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I'm aware that there is numerous systems for figuring out the day of the week at a
specific date, I've never bothered to learn any of them.

I find myself in need of being able to define a birthday fairly quickly mentally.

Because it's just for birthdays only 1910 to 2022 is important, can anyone recommend a
formula to figure out this date quickly?

Feel free to post here or pm me, thanks.
FrankFindley
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Inner circle
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Quote:
On Apr 11, 2023, Fedora wrote:
Because it's just for birthdays only 1910 to 2022 is important, can anyone recommend a
formula to figure out this date quickly?


By "figure out this date quickly", do you mean you want to know the day of week based on the calendar date?

The typical way you determine the day from the date is through an equation which takes into account the Month, Date, and year:

Day of Week = Month Code + Date + Year Code (Mod 7)

In your desired range, you still have to deal with each of these variables. So I don't see a way to simplify the approach.
Michael Daniels
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Isle of Man
1609 Posts

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Quote:
On Apr 12, 2023, FrankFindley wrote:
Quote:
On Apr 11, 2023, Fedora wrote:
Because it's just for birthdays only 1910 to 2022 is important, can anyone recommend a
formula to figure out this date quickly?


By "figure out this date quickly", do you mean you want to know the day of week based on the calendar date?

The typical way you determine the day from the date is through an equation which takes into account the Month, Date, and year:

Day of Week = Month Code + Date + Year Code (Mod 7)

In your desired range, you still have to deal with each of these variables. So I don't see a way to simplify the approach.


Yes, that's the standard approach. The Year codes are simple enough and, with the method I use, the 20th century (19xx) doesn't require a year code (i.e., it is zero). The other thing you always have to take into account is a correction for leap years.

Mike
wulfiesmith
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Beverley, UK
1339 Posts

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Has to be Day One by Scott Cram ...