20170110, 00:07  #1 
Jan 2017
3 Posts 
Unorthodox approach to primes
Hello Interested,
I sometimes just play with numbers, write programs in C# for tests and one day I was playing around with Numerology, not to predict anything, just to see how it behaved. Numerology has many different forms and uses. I might have been even unorthodox in that. What I did was reduce/simplify any number to a single digit, 1 to 9, by adding each digit in a number and if the result was larger then 10, repeat the process. A few examples on what I did: 23 = 2+3 = 5. 55 = 5+5 = 10 = 1+0 = 1. 287 = 2+8+7= 17 = 1+7 = 8. Next I wrote down the products of multiplication 0 to 10. And the result was quite amazing. x 0 1 2 3 4 5 6 7 8 9 10 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 2 3 4 5 6 7 8 9 1 2 0 2 4 6 8 1 3 5 7 9 2 3 0 3 6 9 3 6 9 3 6 9 3 4 0 4 8 3 7 2 6 1 5 9 4 5 0 5 1 6 2 7 3 8 4 9 5 6 0 6 3 9 6 3 9 6 3 9 6 7 0 7 5 3 1 8 6 4 2 9 7 8 0 8 7 6 5 4 3 2 1 9 8 9 0 9 9 9 9 9 9 9 9 9 9 10 0 1 2 3 4 5 6 7 8 9 1 (sorry, I couldn't find any table insert to make it more readable) (It might become clearer by writing them down self then looking at it.) The first thing, that caught my eye, while writing the numbers down was that the table for 8, neatly counted backwards, 8, 7, 6, 5, 4, 3, 2, 1 (8, 16, 24, 32, 40, 48, 56, 64, (72*, 80)) and that all numeroligical values for the table of 9 were all 9s. Further I noticed that the 2 and 7 are each others opposite and the 2 returns first the even numbers then the odd numbers and the 7 returns the odd numbers first then the even numbers. 2 => 2,4,6,8,1,3,5,7 7 => 7,5,3,1,8,6,4,2 The results of the 4 and 5 seems also to be each others opposite while jumping numbers. 4 => 4,8,3,7,2,6,1,5 5 => 5,1,6,2,7,3,8,4 It looks as if the table flips and then can be folded onto itself at 4 and 5, but the 3 and the 6 prevent this. The 3 returns a repeating sequence of 3,6,9,3,6,9,ect, where the 6 returns 6,3,9,6,3,9,6,3,9,ect (and the 9 only 9s) Here only the 3s and 6s are flipped 6,9,3 and 3,9,6. 3 => 3,6,9,3,6,9,3,6,9,3 6 => 6,3,9,6,3,9,6,3,9,6 *I kept on playing with the numbers and found that the value of 9 and 0 in any number is the same when simplifying a number numerologicly this way: 394 = 3+9+4= 16 = 1+6 = 7 304 = 3+0+4 = 7 5979 = 5+9+7+9 = 30 = 3+0 = 3. 5079 = 5+0+7+9 = 21 = 2+1 = 3. 5070 = 5+0+7+0 = 12 = 1+2 = 3. Then I got interested in primes, as I knew we were searching for the largest prime (possible) and wondered if it could be used in anyway. And what brought me here was Tesla's map for multiplication made by Joey Grether that I stumbled upon by accident on the net. I had made something similar in the past, before I had a pc, a table with numbers and reasoned that no prime other then 2, 3, 5 and 7 would be a product in any math table. I had written down numbers and was looking for an easy way to eliminate all products and have the prime numbers remain. I wrote down horizontally all numbers starting with 0 untill I reached the end of my paper. Then a second row of numbers where below the 1 came the 10 and below the 2 came 11 as 10 = 1+0 =1 and 11 = 1+1 =2, ect. Under the 10 came the 19 and under the 11 came 20 as 1+9 = 10 = 1+0 = 1 and 20 = 2+0 = 2. (this also allowed me to create a negative field of numbers.) I took a ruler and striped away numbers that would be part of any table of x. This was a long time ago but I remember the 3, 6 and 9 were a straight vertical line. 2, 4, 8 were diagonal lines and I believe 5 and 10 were diagonal the other way. The only number that did not create a straight line but was jagged and jumping was the 7. (found it most interested) But I had my all prime numbers, I believe to up to 300. No pc or any books I had to create my own way of finding them quickly I started researching them applying numerology to see if there was any pattern. And I thought I found one, until later I wrote a program in C# and the pattern broke. (if it wasn't a bug btw) But it broke on some very special prime(like) numbers that I sadly don't remember the name for. My program ran upto a number as large as a computer integer testing for primes numerological. But this was my finding regarding primes: If a potential prime number's numerological value is a 3, 6 or 9, it is not a prime. So a number like 23354749381, that could be a prime, if it's numerological value is not a 3, 6 or 9. 2+3+3+5+4+7+4+9+3+8+1 = 49 = 4+9 = 13 = 1+3 = 4, not a 3, 6 or 9 it could be a prime. Swapping the 9 with a 0 also returns a numerological value of 4. 678453967653679 = 6+7+8+4+5+3+9+6+7+6+5+3+6+7+9 = 91 = 9+1 = 10 = 1+0 = 1, a possible prime. Maybe it can be of any use for any real mathematicians as they can delve deeper in this. Since I am not one myself my researching capabilities are limited. But if there is something about it, I really really would love to know your findings. Hope it helps. Regards, Erkan Karaagacli 
20170110, 00:17  #2 
P90 years forever!
Aug 2002
Yeehaw, FL
7,489 Posts 
Welcome to the forum. Glad to see you are enjoying exploring the properties of numbers.
The process you describe is called "casting out nines": https://en.wikipedia.org/wiki/Casting_out_nines This is a wellknown shortcut to see if a number is divisible by 3 
20170110, 00:51  #3  
"Forget I exist"
Jul 2009
Dumbassville
10000011000000_{2} Posts 
Quote:
Last fiddled with by science_man_88 on 20170110 at 00:56 

20170110, 01:56  #4  
Jan 2017
3 Posts 
@Science_man_88
Thanks for the TeX table. I'll edit my post later if I have more time. I had never heard of digit sum, just read about it in wiki. It looks like digit sum. Quote:
8+4+0+0+1 = 13 = 1+3 = 4 (not 13) @Prime95 Quote:
But how I use it wouldn't be true for prime numbers that end on a 9 (and would change that to a 0). 3539 is a prime number. 3530 isn't a prime number. 3539 = 3+5+3+9 = 20 = 2+0 = 2. 3530 = 3+5+3+0 = 11 = 1+1 = 2. [in general] It is about telling if a number is a prime number by adding all digits and continuing adding the digits of the result if the result is 10 or larger until 1 digit is left. Hope you understand it is not about the known digit sum and casting out nines, though very similar yes. Last fiddled with by Erkan on 20170110 at 02:22 

20170110, 02:22  #5 
Aug 2006
13541_{8} Posts 
It's the digital root, which is related but not identical to the digital sum. The digital root is just a stone's throw away from being the residue (mod 9) and has most of its properties in common with it.

20170110, 02:24  #6  
"Forget I exist"
Jul 2009
Dumbassville
2^{6}·131 Posts 
Quote:
Tried to add color to showcase a few other properties but didn't get it to work. Thanks to CRG for the correction to the name. Last fiddled with by science_man_88 on 20170110 at 02:29 

20170110, 02:52  #7 
Jan 2017
3 Posts 
[on a side note and Off Topic and thanks for the table btw :) ]
Something interesting happens if you add the 'digit sum' results of the products [digit sum results of the products of the multiplication tables 0 to 10] 1+2+3+4+5+6+7+8+9+1 = 46 = 4+6 = 10 = 1 2+4+6+8+1+3+5+7+9+2 = 47 = 4+7 = 11 = 2 3+6+9+3+6+9+3+6+9+3 = 48 = 4+8 = 12 = 3 4+8+3+7+2+6+1+5+9+4 = 49 = 4+9 = 13 = 4 (corrected this one, sorry) 5+1+6+2+7+3+8+4+9+5 = 50 = _______ = 5 6+3+9+6+3+9+6+3+9+6 = 60 = _______ = 6 7+5+3+1+8+6+4+2+9+7 = 52 = _______ = 7 8+7+6+5+4+3+2+1+9+8 = 53 = _______ = 8 9+9+9+9+9+9+9+9+9+9 = 81 = _______ = 9 1+2+3+4+5+6+7+8+9+1= 46 = 4+6 = 10 = 1+0 =1 I made some numbers bold as to hint. And with all and the above, it's all very similar but not quite. Just let what you have learned go for a minute. I added unorthodox for a reason. It's not the math you learn at school. :) (hope I didn't make any other mistakes it's late here :) ) Last fiddled with by Erkan on 20170110 at 03:01 
20170110, 03:34  #8 
Aug 2006
3^{2}×5×7×19 Posts 
I would have thought that digital roots would be used as an introduction to modular arithmetic in many schools...

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