Can You Calculate Any Dates Day of the Week in 1-2 Minutes?
“If you spend a bit learning the system, you can calculate any date's position in the week in no more than a minute or two”
Summary
Once you learn a mental algorithm (e.g., the Doomsday rule or similar methods), you can determine the weekday for any Gregorian date in well under a minute—often in just a few seconds. Demonstrations and instructional sources confirm that the calculation can be performed quickly enough to meet the claim.
Sources 60 searched
- Determination of the day of the week - Wikipedia
The letter for any date will be found where the row containing the month (in black) at the left of the "Latin square" meets the column containing the date above the "Latin square". The Sunday letter will be found where the column containing the century (below the "Latin square") meets the row ...
- Doomsday rule - Wikipedia
The technique applies to both the ... algorithm is simple enough that it can be computed mentally. Conway could usually give the correct answer in under two seconds....
- Find day of the week for a given date - GeeksforGeeks
The function should return values from 0 to 6 where 0 means Sunday, 1 Monday and so on. ... Input: d = 30, m = 8, y = 2010 Output: 1 Explanation: 30th August 2010 was a Monday. Input: d = 15, m = 6, y = 1995 Output: 4 Explanation: 15th June 1995 was a Thursday. Input: d = 29, m = 2, y = 2016 Output: 1 Explanation: 26th January was a Monday. ... The Formula-Based Approach for calculating the day of the week is an efficient method that calculates the day using simple arithmetic operations.
- On what day of the week were you born? | plus.maths.org
Since 25 May 1961 is a Thursday, it will be Thursday again 425 weeks later, and 3 days after that will be a Sunday. So, 20 July 1969 is a Sunday. Ta da! But let's be realistic. It is very unlikely that you could perform these calculations quickly enough to impress anyone.
- Mentally calculating the day of the week
This post will present an alternative method that’s easier to use in practice and can be described more succinctly. Here’s the algorithm. Take the last two digits of the year and add the number of times 4 divides that number. Add a constant corresponding to the month. Add the day of the month.
- 5 Ways to Calculate the Day of the Week - wikiHow
At the time that he taught me the algorithm, he could calculate the day of the week in his head for ANY date on the Gregorian calendar in 3 seconds flat. Watch this performance by Arthur “Art” T. Benjamin[3], the “Mathemagician” and a math professor at Harvey Mudd College, if you doubt that the algorithm can be performed this quickly: https://www.ted.com/talks/arthur_benjamin_a_performance_of_mathemagic.
- How to Find the Day of the Week for Any Date | The Old Farmer's Almanac
Divide the sum by 7. The remainder is the day of the week! One is Sunday, two is Monday, and so on. If there is no remainder, the day is Saturday. [Note: At this step, it may be easiest to use long division to get the remainder.
- How to determine the day of the week, given the month, day and year
Because the leap year pattern also recurs with a four hundred year cycle, a simple table of four hundred elements, and single modulus, suffices to determine the day of the week (in the Gregorian Calendar), and does it much faster than all the other algorithms proposed.
- How to Calculate the Day of the Week from Any Date | Art of Memory
This problem can be easily fixed by checking for a subtotal of 0 before subtracting the Leap Year Code. In this case you want your final answer to be 6 or Saturday. To illustrate my point look at what happens when you calculate for the week day February 27, 2016:
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