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Topic: Phi day coming
Message: Posted by: Jimso (Jan 19, 2017 10:07AM)
For the mathemagic geeks among us, I wanted to point out the next January 6 (1/6/18) will be a significant Phi day*, which the media will undoubtedly bring to public attention. It will present a perfect opportunity to show our stuff. The question is, does anyone know of magic tricks involving this number? To be clear, I am not looking for tricks that use some hidden principle involving Phi, but any that openly celebrate the glory of Phi in any of its many variants. We have almost a year to discuss ideas and maybe come up with some gems.

*Phi (also known as the golden ratio, the divine proportion, and other names) is a naturally mysterious number (approximately 1.618) that shows up in astonishingly diverse ways. If you are unaware, do a quick search on the internet or consult one of the many books written about it.
Message: Posted by: Larry Barnowsky (Jan 22, 2017 04:05PM)
In my book [url=barnowskymagic.com]Magica Analytica[/url] I included between main chapters a little prediction effect based on Phi, The Golden Ratio.
It's on pages 80 and 94.
The letter Phi was chosen to honor Phidias a Greek architect who used the Golden Ratio in designing the statues in the Parthenon. It also is the Greek letter which sounds like F, in honor of Fibonacci. The ratio of pairs of numbers in the Fibonacci sequence converges to Phi = 1.6180339887...

Larry :readingbook:
Message: Posted by: Jimso (Jan 6, 2018 09:21AM)
Phi day is here. Is there no one but Larry who knows any tricks with Phi? It has so many mysterious and interesting properties, it should be a natural.
Message: Posted by: wunceaponatime (Jan 10, 2018 12:22PM)
Phee phi pho fum
Message: Posted by: WojciechW (Jun 16, 2018 06:14AM)
If you like phi-powered tricks, search for "[b]F-16 by Wojciech Warpechowski[/b]".
Message: Posted by: farmerkarl (Jun 22, 2018 01:37AM)
Looks like it might be quite a while until a next Phi day....
Message: Posted by: blackstone99 (Jul 7, 2018 09:24AM)
Why Phi? :)
Message: Posted by: WojciechW (Jul 7, 2018 12:28PM)
[quote]On Jul 7, 2018, blackstone99 wrote:
Why Phi? :) [/quote]

That is a deep question ;)

If you asked [i]why Phi?[/i], I will answer: because it IS magical number with some great properties (like [b]1/phi = phi-1[/b]).

If you asked just [i]why 1/6/18 was a Phi Day?[/i] the answer is straightforward: phi = 1.618...

I think, that with a little "magic", we can create another Phi Days in the near future.
Getting valid days and months shouldn't be hard.
Getting year number in the near future can be little tricky.

[b]OBTAINING YEAR 2018 when you already have used 18 (3rd and 4th phi digit) to calc day/month:[/b]

Let phi = 1.6180339887... (from Wiki)
Let's make sum of all phi digits presented by Wiki:
1+6+1+8+0+3+3+9+8+8+7 = 54
Year is 3rd element in the date formats in US and EU, so we can use this as a pretext to divide above sum by 3 and obtaining the year 2018 in this way:
54 / 3 = 18

[b]If you still can use 4th and 5th phi digit:[/b]
Let phi = 1.6180...
Make sum of 4th and 5th digit:
8+10 = 18

[b]OBTAINING YEAR 2019:[/b]

Let phi = 1.61803...
Sum all digits:
1+6+1+8+0+3 = 19

[b]Or in more sophisticated way:[/b]
Let phi = 1.61803398...
Step 1:
Use first digit (1) for the month or day
Step 2:
Sum all digits after the decimal point:
6+1+8+0+3+3+9+8 = 38
Divide this sum by 2 (can be the step number, or number of digits representing year [YY]) to generate the year:
28 / 2 = 19

[b]Generating valid days and months is easier and can be done like that:[/b]
Using US date format: MM/DD/YY

MM can be:
A. 1 (first digit)
B. 7 (sum of 1st and 2nd digit: 1+6)
C. 7 (sum of 1st and 2nd digit after the decimal point: 6+1)

DD can be:
A. 6 (2nd digit of phi)
B. 9 (sum of 3rd and 4th digit of phi: 1+8)
C. 8 or 18 (sum of 3rd and 4th digit after the decimal point: 8+0 or 8+10)

Just remember that EU date format is DD-MM-YY (so 18 in the last example is a valid day in US but not a valid month in EU!)