## Left Trunctable Primes

As a counterpoint to my story "Right Trunctable Primes", the curious will be satisfied to know there ARE Left Trunctable Primes as well, which are prime numbers that remain prime when the leading digit is removed successively. Here are some: 2, 3, 5, 7, 13, 17, 23, 37, 43, 47, 53...
freeed
66-70, M
2 Responses
3
Jan 4, 2012

## Is 2,904,897 A Prime Number?

This little trick may win a bar bet someday and it's inexplicable on the surface, so is cool just for that. Well, it's not EVEN, so isn't a multiple of 2, doesn't end in 5, so isn't divisible by 5, but that leaves a lot of ground. In case you forgot, you only have to divide a...
freeed
66-70, M
10 Responses
4
May 26, 2010

## Is 59595 A Prime Number?

No, silly, any number ending in 5 is divisible by 5. Why did this number come up? It's how many EP points I reached as of today and I've always thought "symmetrical numbers" are cool. BTW, is the number of EP points YOU have a prime number?
freeed
66-70, M
0
Apr 16, 2011

## The Only 'even' Number That I Like Is 2

I don't know how I got into the 'prime number thing', but now, when I set my microwave oven or dryer for time, it has to be a prime number. I'm not totally obsessed with prime numbers...they can just be odd numbers; but even number drive me nuts... with the exception of 2, which...
fishsweeper
56-60, F
0
Apr 23, 2012

## I almost became a computer criminal at 17 years

old because of a fascination with prime numbers. I had just read Rivest Shamir and Adlemans article in the 1979 issue of Scientic American on Nondeterministic Polynomail Time Problems. In it they detail the workings of public key cryptosystems, that are used in your browser...## All you Prime Number freaks.

.... What books on the Theory of Numbers have you people liked, from general interest, to textbooks and the like.....
atenra11
46-50, M
2 Responses
0
Nov 4, 2014

## Does 1910194 Mean Anything To You?

It appears in the book Japa Yoga by Svami Sivananda and I always wondered what its significance is - the book's context isn't explicit. It would have been cooler if it were 1910191. Neither of these 2 are prime numbers, however. FYI the next smaller number which is prime is...
freeed
66-70, M
1 Response
1
Apr 16, 2011

## Why I Love Prime Numbers

I didn’t always like prime numbers. For Pete’s sake, dividing by 2 is always easier… and 10 is a fabulous number if you’re doing any arithmetical work. I discovered the beauty of prime numbers totally by accident. I inadvertently set a timer for 59 minutes. It just...
fishsweeper
56-60, F
4 Responses
5
Aug 24, 2012

## Right Trunctable Primes

These are strange primes in that, if you successively remove the right-most digit another prime results, BUT even stranger is that if you coninue to do this, every "new [smaller]" number will also be prime. Here's an example: 3797 379 37 3...
freeed
66-70, M
4 Responses
5
Apr 18, 2010

## Prime Numbers

Sieve_of_Eratosthenes_animation.gif (445 × 369 pixels, file size: 154 KB, MIME type: image/gif, looped, 159 frames, 37s)## I Think That I Must Have Lost Some IQ Points!

When I was a kid in both Junior-High and High School, I was tested, and my IQ scores were 165 and 185. I could figure out puzzles and riddles, decipher codes, analyze situations, size up people, and do a plethora of 'brainy' other stuff way back when. Later, I gave birth to 5...
fishsweeper
56-60, F
5 Responses
3
Apr 29, 2012

## Anyone Else Solve That Google Riddle To Find The First 10 Digit Prime In E?

If so, how? I hacked my way through it using microsoft excel (cause I'm not a coder) took a few hours but very fun! http://www.npr.org/templates/story/story.php?storyId=3916173
dlmolicares
36-40
2 Responses
1
May 4, 2012

## I AM 177

I happened on this group by 'accident' (although, in reality, there are really no accidents). Anyway, if I am permitted to join, that would make me no. 177 (another prime number). I am also writing this on Saturday, the seventh day of the week (yet another prime).
leprechaunz
56-60, M
0
Sep 20, 2013

## Ahhh The Number 13, It Always Fascinates Me..

I love the number 13 as much as people hate it, along with the number 17, wherever i go i use the number 13 in whatever thing i do!!
brokenwings13
22-25, M
0
Apr 25, 2011