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## #1 2012-11-19 13:00:41

mathgogocart
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Registered: 2012-04-29
Posts: 1,426

### post prime numbers!

We will post prime numbers and say something intrssting about the number
So lets start
3!
the unluck number:|:|:|:|

Hey.

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## #2 2012-11-19 18:51:32

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,886

### Re: post prime numbers!

2-the only even prime.

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

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## #3 2012-11-29 19:59:25

mathaholic
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From: Juliania
Registered: 2012-11-29
Posts: 2,836
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### Re: post prime numbers!

5-number of fingers on your hand!!!

"Double the fun, double the thrill, double the coolness" - Julianthewiki

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## #4 2012-11-30 07:55:59

noelevans
Member
Registered: 2012-07-20
Posts: 236

### Re: post prime numbers!

7  One of the few primes whose reciprocal is easy to remember.

For 1/7:  2*7=14, 2*14=28,  2*28+1=57 ; that is, keep doubling the denominator till you reach
56 then add the numerator to the 56 to get the last two digits of 1/7 which is a repeating .142857.

Of course 1/2, 1/3, 1/5 and 1/11 aren't bad either.

Writing "pretty" math (two dimensional) is easier to read and grasp than LaTex (one dimensional).
LaTex is like painting on many strips of paper and then stacking them to see what picture they make.

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## #5 2012-11-30 16:19:38

mathaholic
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From: Juliania
Registered: 2012-11-29
Posts: 2,836
Website

### Re: post prime numbers!

13- number of different cards in a deck

"Double the fun, double the thrill, double the coolness" - Julianthewiki

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## #6 2012-12-06 10:53:41

noelevans
Member
Registered: 2012-07-20
Posts: 236

### Re: post prime numbers!

11 --- one of the few primes larger than 10 that it is easy to multiply by.  To multiply a number, say
3142 by 11 just put a zero in front and behind it, like so 031420 and then add consecutive pairs of
digits (typically from right to left since in some cases there may be carries) and record these sums:
0+3, 3+1, 1+4, 4+2, 2+0 ; that is, 34562.  If a sum exceeds 9 then carry 1 to the next sum for example 23572 ---> 0235720 --->  2 5 8 12 9 2 = 2 5 9 2 9 2; that is, 259292 carrying the 1
from the 12 into the 8 in the next column to the left.  With a little practice this can be done quickly

Last edited by noelevans (2012-12-06 10:55:06)

Writing "pretty" math (two dimensional) is easier to read and grasp than LaTex (one dimensional).
LaTex is like painting on many strips of paper and then stacking them to see what picture they make.

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## #7 2012-12-06 11:02:15

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,886

### Re: post prime numbers!

19-the first prime with the sum of its digits equal to 10.

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

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## #8 2012-12-06 11:04:56

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,230

### Re: post prime numbers!

23

John Forbes Nash's favorite prime number.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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## #9 2012-12-06 11:07:18

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,886

### Re: post prime numbers!

Boy, was that guy an ugly fellow!

97-largest prime below 100.

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

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## #10 2012-12-06 11:12:48

mathgogocart
Member
Registered: 2012-04-29
Posts: 1,426

### Re: post prime numbers!

131-the number that is ALSO PSELLED BCAKWARDS...OMG

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## #11 2012-12-07 13:02:03

noelevans
Member
Registered: 2012-07-20
Posts: 236

### Re: post prime numbers!

13 --- a baker's dozen.

Writing "pretty" math (two dimensional) is easier to read and grasp than LaTex (one dimensional).
LaTex is like painting on many strips of paper and then stacking them to see what picture they make.

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## #12 2012-12-07 13:32:50

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,886

### Re: post prime numbers!

23-number of characters in "greengrocers apostrophe"

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

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## #13 2012-12-07 13:49:18

noelevans
Member
Registered: 2012-07-20
Posts: 236

### Re: post prime numbers!

Three digit numbers with two 3's and one 1 or with two 1's and one 3.  Only one of them is NOT a
prime.

Writing "pretty" math (two dimensional) is easier to read and grasp than LaTex (one dimensional).
LaTex is like painting on many strips of paper and then stacking them to see what picture they make.

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## #14 2012-12-07 14:07:18

noelevans
Member
Registered: 2012-07-20
Posts: 236

### Re: post prime numbers!

2 --- the only number for which any positive integer can be written as a sum of non-negative powers of that number alone using each power of the number no more than once.

Writing "pretty" math (two dimensional) is easier to read and grasp than LaTex (one dimensional).
LaTex is like painting on many strips of paper and then stacking them to see what picture they make.

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## #15 2012-12-08 04:57:56

mathgogocart
Member
Registered: 2012-04-29
Posts: 1,426

### Re: post prime numbers!

101-1-1=0-the first sensible number

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## #16 2012-12-13 18:04:34

mathaholic
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From: Juliania
Registered: 2012-11-29
Posts: 2,836
Website

### Re: post prime numbers!

Last edited by julianthemath (2012-12-13 18:05:18)

"Double the fun, double the thrill, double the coolness" - Julianthewiki

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## #17 2012-12-16 04:41:41

mathgogocart
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Registered: 2012-04-29
Posts: 1,426

### Re: post prime numbers!

111 3 digits repeated trpile

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## #18 2012-12-17 16:58:44

mathaholic
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From: Juliania
Registered: 2012-11-29
Posts: 2,836
Website

### Re: post prime numbers!

Mathgogocart, 111 is not prime. It is divisible by 1, 3, 37, 111 (ay be incomplete).

"Double the fun, double the thrill, double the coolness" - Julianthewiki

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## #19 2013-01-07 13:27:05

mathgogocart
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Registered: 2012-04-29
Posts: 1,426

2

Hey.

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## #20 2013-01-07 13:29:40

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,230

### Re: post prime numbers!

I think you already picked 2.

101 - a room with a special meaning.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Online

## #21 2013-01-11 21:42:44

mathaholic
Member
From: Juliania
Registered: 2012-11-29
Posts: 2,836
Website

### Re: post prime numbers!

bobbym wrote:

101 - a room with a special meaning.

What is the special meaning?
17-the sum of the first four primes.

"Double the fun, double the thrill, double the coolness" - Julianthewiki

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## #22 2013-01-12 00:15:43

scientia
Member
Registered: 2009-11-13
Posts: 222

### Re: post prime numbers!

According to the Old Testament, 31 kings were defeated by Joshua after the children of Israel had crossed the river Jordan (Joshua 12:924).

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## #23 2013-01-12 06:38:21

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,230

### Re: post prime numbers!

1111111111111111111

The second repunit that is prime.

julianthemath wrote:

What is the special meaning?

You are a little young yet but some day you will read 1984.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Online

## #24 2013-01-12 12:05:42

mathaholic
Member
From: Juliania
Registered: 2012-11-29
Posts: 2,836
Website

### Re: post prime numbers!

Oh, okay.
113-the 30th prime.

"Double the fun, double the thrill, double the coolness" - Julianthewiki

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## #25 2013-01-12 12:26:51

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 83,230

### Re: post prime numbers!

11111111111111111111111 the 3rd repunit that is a prime.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Online