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## #26 2013-01-22 09:06:38

Member
Registered: 2013-01-22
Posts: 116

### Re: Prime Numbers!!

For prime numbers (p), under 3 squared; p = 2a + 1 (where a = any whole number)
For prime numbers (r), under 5 squared; r = 3p +/- 2 or 4
For prime numbers (i), under 7 squared; i = 5r +/- 6 or 12 or 18 or 24
For prime numbers (m), under 11 squared; m = 7i +/- 30 or 60 or 90 or 120 or 150 or 180
For prime numbers (e), under 13 squared; e = 11m +/- 210 or 420 or 630 or 840 or 1050 or 1260 or 1470 or 1680 or 1890 or 2100

(A no. divisible by a, but not divisible by a group b +/- A no. divisible by group b, but not a = A no. not divisible by a or b.)

* Some rules give 1 but this is not prime.

"Time not important. Only life important." - The Fifth Element 1997

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## #27 2013-01-22 10:54:12

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,015

### Re: Prime Numbers!!

Welcome to the forum!

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #28 2013-01-22 13:09:17

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,199

### Re: Prime Numbers!!

Welcome to the forum!

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #29 2013-01-25 12:02:14

n872yt3r
Member
Registered: 2013-01-21
Posts: 392

### Re: Prime Numbers!!

Prime numbers are numbers that have no other factors then one and itself. One is not a prime number... 1x1=1 and 1/1=1.
x = prime
y = anything other than 1 and x
z = composite
a = decimal
x/1=x. x/x=1. x/y=a.
z/1=z. z/z=1. z/y=y.
For something else on prime numbers... go to my Sieve of Eratosthenes post.

- n872yt3r
Math Is Fun Rocks!
By the power of the exponent, I square and cube you!

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## #30 2014-06-25 08:33:21

cmowla
Member
Registered: 2012-06-14
Posts: 61

### Re: Prime Numbers!!

kerr wrote:

http://en.wikipedia.org/wiki/Largest_known_prime_number
How is 17,425,170 a prime number? It is divisible by 2.
Thanks

It clearly says in plain English that this number is the number of digits of the largest known prime number.  You're welcome?

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## #31 2014-06-25 11:01:24

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,199

### Re: Prime Numbers!!

Hi kerr;

is the prime number.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #32 2014-06-27 09:39:51

Member
Registered: 2013-01-22
Posts: 116

### Re: Prime Numbers!!

2+/-1..
6+/-1 5..
30+/- 1 7..
210 +/- 1 11..
2310 +/- 1 13..

equals primes......to a certain point above highest prime squared. e.g.>9,25,49,121 or 169 accordingly. And so on but the numbers get very big but you can do this up to infinity.

"Time not important. Only life important." - The Fifth Element 1997

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## #33 2014-08-16 02:50:25

Member
Registered: 2013-01-22
Posts: 116

### Re: Prime Numbers!!

The primes there are in a certain range can be estimated because there are;
1 No. not factorable by 2 in (2)
There are 2 No.'s not factorable by 2 or 3 in (6)
There are 8 No.'s not factorable by 2 or 3 or 5 in (30)
There are 48 No.'s not factorable by 2 or 3 or 5 or 7 or in (210)
times 48 by (prime -1) to get the next number of no.'s. i.e. =480 no.'s in (2310) not factorable by 2,3,5,7, or 11.....and so on.

"Time not important. Only life important." - The Fifth Element 1997

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