40th Mersenne Prime Found
michael posted more than 9 years ago  from the primalurges dept.
99FenwayFrank writes "A release from New Scientist announces that the Great Internet Mersenne Prime Search found another one: 2^20996011  1 is prime. Weighing in at 6,320,430 digits (6 megabytes of prime number...), it becomes the world's largest. Slashdot readers may remember then announcement of the 39th Mersenne Prime, a mere 3.5 million digits."
Fraud (5, Funny)
addaon (41825)  more than 9 years ago  (#7613311)
Wait, no, it just got slashdotted before it fully loaded...
Re:Fraud (0)
Anonymous Coward  more than 9 years ago  (#7613658)
Re:Fraud (2, Informative)
Anonymous Coward  more than 10 years ago  (#7614193)
2^11 mod 10 = 1
2^21 mod 10 = 3
2^31 mod 10 = 7
2^41 mod 10 = 5
2^51 mod 10 = 1
2^61 mod 10 = 3
2^71 mod 10 = 7
2^81 mod 10 = 5
etc.
20996011 mod 4 = 3 so it's a 7.
interesting (2, Funny)
nocomment (239368)  more than 10 years ago  (#7614283)
Re:interesting (1)
fatphil (181876)  more than 10 years ago  (#7615358)
tugs forelock
While I'm here I must show due respect to GIMPS for harnessing hundreds of
thousands of PCs and bulldozing so convincingly through these ranges.
Phil
Re:interesting (1)
arvindn (542080)  more than 10 years ago  (#7619480)
Sure we do! [wikipedia.org]
BTW, Remember me? :)
SLASHDOT!!! (0)
Anonymous Coward  more than 9 years ago  (#7613322)
Finally! (4, Funny)
Rick the Red (307103)  more than 9 years ago  (#7613504)
Efficient factoring algorithm (1)
Peter Millerchip (166655)  more than 10 years ago  (#7619548)
Re:Finally! (1)
SamSim (630795)  more than 10 years ago  (#7635240)
Re:Finally! (1)
Chris_Jefferson (581445)  more than 10 years ago  (#7637778)
ObTiredOldJoke (0, Redundant)
dacarr (562277)  more than 9 years ago  (#7613337)
Here's something stupid to do. (5, Funny)
satanami69 (209636)  more than 9 years ago  (#7613351)
I wonder who has the most occurrences.
Re:Here's something stupid to do. (0)
Anonymous Coward  more than 9 years ago  (#7613368)
Re:Here's something stupid to do. (3, Insightful)
infornogr (603568)  more than 9 years ago  (#7613386)
Re:Here's something stupid to do. (1)
GigsVT (208848)  more than 9 years ago  (#7613393)
Re:Here's something stupid to do. (0)
Anonymous Coward  more than 9 years ago  (#7613572)
Re:Here's something stupid to do. (1)
KDan (90353)  more than 9 years ago  (#7613711)
Daniel
Re:Here's something stupid to do. (1)
dacarr (562277)  more than 9 years ago  (#7613491)
Re:Here's something stupid to do. (1)
dacarr (562277)  more than 9 years ago  (#7613520)
Re:Here's something stupid to do. (1)
Carnildo (712617)  more than 9 years ago  (#7613695)
Re:Here's something stupid to do. (0)
Anonymous Coward  more than 10 years ago  (#7613866)
Re:Here's something stupid to do. (1)
PhuCknuT (1703)  more than 10 years ago  (#7614168)
Re:Here's something stupid to do. (1)
BhAaD (692949)  more than 10 years ago  (#7614328)
Re:Here's something stupid to do. (1)
Naikrovek (667)  more than 10 years ago  (#7615757)
Re:Here's something stupid to do. (2, Informative)
Muad'Dave (255648)  more than 10 years ago  (#7618088)
You guys are unblocking the file before searching, right? You'll miss instances of your that wrap around eol. Use:
I bet it's not that big (3, Funny)
Anonymous Coward  more than 9 years ago  (#7613502)
Wow! (3, Funny)
HoldmyCauls (239328)  more than 9 years ago  (#7613526)
Hah, you really thought I actually counted for a second there!
Re:Wow! (1)
JeffMagnus (133746)  more than 10 years ago  (#7614771)
Get it straight leetboy.
40th? (4, Insightful)
Tom7 (102298)  more than 9 years ago  (#7613527)
Re:40th? (0)
Anonymous Coward  more than 10 years ago  (#7621844)
Time to update all pages (4, Informative)
Anonymous Coward  more than 9 years ago  (#7613560)
Well, now it is 40 known Mersenne Primes, and also 6 discovered by the GIMPS: they need to change the front page to reflect this, and also some banners ("the largest 5 Mersenne primes").
I think it's worth noting that GIMPS not only discovers new Mersenne primes, but also is the discoverer of the biggest six known ones.
Awesome! (4, Funny)
falsification (644190)  more than 9 years ago  (#7613577)
Re:Awesome! (1)
fmlug.org (695374)  more than 10 years ago  (#7613883)
Re:Awesome! (0)
Anonymous Coward  more than 10 years ago  (#7614130)
Too bad nobody knows if there even are 42 of them. It's conjectured that Mersenne primes are infinite in number but this has not been proven. There could be only 40.
math == piracy (3, Funny)
Anonymous Coward  more than 9 years ago  (#7613724)
the RIAA is lobbying to have mathematics outlawed due to the $400 billion lost yearly to these illegal primes.
remember kids, learning math makes you a pirate! stick to watching TV and eating delicious Oreo(R) cookies!
not prime (0)
Anonymous Coward  more than 9 years ago  (#7613736)
Nope, divisible by 2.
Re:not prime (0)
Anonymous Coward  more than 9 years ago  (#7613770)
Re:not prime (0)
Anonymous Coward  more than 10 years ago  (#7613824)
Re:not prime (1)
luckyguesser (699385)  more than 10 years ago  (#7613841)
with one exception
Re:not prime (0)
Anonymous Coward  more than 10 years ago  (#7613901)
Re:not prime (1)
luckyguesser (699385)  more than 10 years ago  (#7613920)
Any expression
2^n
where n is a positive integer will be even,
and subtracting 1 will make it odd.
Re:not prime (0)
Anonymous Coward  more than 10 years ago  (#7613992)
printf("%d", 2^31);
outputs 0.
Re:not prime (1)
jquirke (473496)  more than 10 years ago  (#7617495)
So effectively you are doing 2 XOR 3  1 = 1  1 = 0
Re:not prime (0)
Anonymous Coward  more than 10 years ago  (#7624840)
While you are correct in that ^ is the exclusiveor operator, your summary of what the code does is incorrect. The expression in the grandparent actually does 2 XOR (3  1) since subtraction has higher precedence [lycoszone.com] than bitwise exclusive or.
In this example, one could easily overlook this since both the correct and incorrect ways of interpreting it yield zero.
Re:not prime (1)
damien_kane (519267)  more than 10 years ago  (#7616176)
(2^209960111) => 2^(209960111)
= 2^(20996010)
So of course, his logic is flawed, but the answer he came up with is correct based on his logic.
(2^20996010)mod 2 = 0
Therefore 2^20996010 is not prime
Maybe this kid should go back to elementary school and be retaught the proper Order of Operations.
Well, that's the way it goes... (5, Informative)
Charbal (677787)  more than 10 years ago  (#7613802)
Of course, it didn't occur to me to take a look at the Science section before submitting my own copy of this story (which, since it has several other useful links in it, follows):
Michael Shafer, a graduate student at Michigan State University [msu.edu] , took time out for a "short victory dance" upon learning his computer had discovered the 40th known Mersenne prime [utm.edu] as part of The Great Internet Mersenne Prime Search [mersenne.org] . The number itself is 2**209960111 and when expressed in base 10, has 6,320,430 digits [wolfram.com] (zipped copy [wolfram.com] ). However, this is not necessarily the 40th Mersenne prime; there could be another between the previous largest known prime (M39=2**134669171, also discovered by GIMPS) and this one. Also worth noting is the stillstanding USD$100,000 EFF prize [eff.org] for the discover of the first prime of at least 10 million (decimal) digits. GIMPS clients are available for various operating systems [mersenne.org] as well as information on how GIMPS would distribute the prize [mersenne.org] . A press release on the achievement [mersenne.org] is available as well as [newscientist.com] several [wolfram.com] articles [utm.edu] . Of course, this also means there's a new largest known even perfect number [utm.edu] in town.
Holy hyperlinks, Batman! (0)
Anonymous Coward  more than 10 years ago  (#7614017)
Damn them! (1, Funny)
nytes (231372)  more than 10 years ago  (#7613977)
Re:Damn them! (1)
JDWTopGuy (209256)  more than 10 years ago  (#7614993)
Re:Damn them! (1)
damien_kane (519267)  more than 10 years ago  (#7616134)
I can't let the cat out of the bag until I find the 43rd and 44th and change all of my passwords.
You silly people... thinking the 40th was good enough... And didn't you learn that you shouldn't use the same password for everything? Now you see why
Re:Damn them! (1)
nytes (231372)  more than 10 years ago  (#7616537)
Hey! That's the combination on my luggage!
HOTEL GREASED UP YODA DOLL (1, Troll)
Anonymous Coward  more than 10 years ago  (#7614018)
Jedi jizz in my hair
Warm smell of anal grease
Rising up through the air
Up ahead in the distance
I saw a frigthening sight
My head grew heavy, and my anas grew slim
I had to stop for the night
There he stood in the doorway
Smelled jedi ass juice smell
And I was thinking to myself
This could be Heaven or this could be Hell
Then he lit up a candle
And he showed me the way
There were voices down the corridor
I thought I heard them say
Welcome to the Hotel Greased Up Yoda Doll
Such a lovely place
Such a lovely place (background)
Such a lovely face
Plenty of room in my anus at the Hotel Greased Up Yoda Doll
Any time of year
Any time of year (background)
You can find him there
You can find him there
His jedi mind is Tiffany twisted
he's got the Mercedes bends
he's got a lot of pretty, pretty faggot boys
That he calls friends
How they dance in the courtyard
Sweet summer glory hole
Some grease their anus to remember
Some grease their anus to forget
So I called up the Captain
Please bring me my lube
He said
We haven't had that spirit here since 1972
And still those voices are calling from far away
Wake you up in the middle of the night
Just to hear them say
Welcome to the Hotel Greased Up Yoda Doll
Such a lovely Place
Such a lovely Place (background)
Such a lovely face
They're livin' it up at the Hotel Greased Up Yoda Doll
What a nice surprise
What a nice surprise (background)
Bring your alibies
Mirrors on the ceiling
Pink intestines on ice
And he said
We are all just prisoners here
Yodas stuffed up our ass
And in the master's chambers
They gathered for the feast
Plunge it up there with their steely knives
But they just can't kill the beast
Last thing I remember
I'm in ecstasy
Greased up yoda doll shoved right up my ass
Relax your anus said the nightman
We are programed for anal recieve
You can plunge that yoda doll up your anus
But you can never leave
If I post the number here... (2, Funny)
Twintop (579924)  more than 10 years ago  (#7614090)
6 Megabytes?????? (0, Troll)
the eric conspiracy (20178)  more than 10 years ago  (#7614104)
This number takes more like 21 KB to represent.
Re:6 Megabytes?????? (0)
Anonymous Coward  more than 10 years ago  (#7614166)
Re:6 Megabytes?????? (1)
Ster (556540)  more than 10 years ago  (#7614293)
Ster
Re:6 Megabytes?????? (1)
Tom7 (102298)  more than 10 years ago  (#7614314)
2^209960111
Seriously, though, where did you get the factor of 300 difference? You think it takes less than a 37th of a bit to represent each digit?
Re:6 Megabytes?????? (1)
the eric conspiracy (20178)  more than 10 years ago  (#7615153)
Pretty simple  binary math  each place of a binary number is a power of two. Since this number is 2^20996011  1, it can be represented in binary form as 20996010 1's, thus 21 KB. It's also why you can count to 2^10  1 on your fingers if you use each finger as a binary digit. If you try counting in ASCII base 10 digits on your fingers you can only count to 9, or 2^3 + 1.
Re:6 Megabytes?????? (1)
Scott Wood (1415)  more than 10 years ago  (#7615420)
Re:6 Megabytes?????? (1)
jareds (100340)  more than 10 years ago  (#7615430)
Re:6 Megabytes?????? (0)
Anonymous Coward  more than 10 years ago  (#7616628)
Re:6 Megabytes?????? (0)
Anonymous Coward  more than 10 years ago  (#7619565)
Re:6 Megabytes?????? (1)
iggymanz (596061)  more than 10 years ago  (#7615710)
Hmm (0)
quantaman (517394)  more than 10 years ago  (#7614177)
Xbox? (1)
k98sven (324383)  more than 10 years ago  (#7614224)
(joke)
6 Megabytes, eh? (2, Informative)
jvmatthe (116058)  more than 10 years ago  (#7614257)
This is all perfectly true, modulo an arithmetic error on my part.
Re:6 Megabytes, eh? (2, Informative)
k98sven (324383)  more than 10 years ago  (#7614317)
If we want it in humanreadable form, convert to base10:
2^20996011 = 10^(20996011*log(2))
20996011*log(2) is about 6,320,000, decimals.
1 decimal = 1 char = one byte = 6 Mb.
Re:6 Megabytes, eh? (1)
jvmatthe (116058)  more than 10 years ago  (#7614440)
Re:6 Megabytes, eh? (1)
cicadia (231571)  more than 10 years ago  (#7614624)
It's not the most compact form, to be sure, but it is, as advertised, 6 megabytes of primey goodness.
Re:6 Megabytes, eh? (1)
jvmatthe (116058)  more than 10 years ago  (#7614727)
Re:6 Megabytes, eh? (1)
Urkki (668283)  more than 10 years ago  (#7616671)
Re:6 Megabytes, eh? (1)
evalhalla (581819)  more than 10 years ago  (#7616669)
I guess that an even more compact way to store it would be the binary representation of 2099601, since we know how to calculate the number.
Of course, it would be waaaay less impressive :)
Re:6 Megabytes, eh? (1)
JohnPM (163131)  more than 10 years ago  (#7617946)
Re:6 Megabytes, eh? (1)
jvmatthe (116058)  more than 10 years ago  (#7618099)
And if someone brings up storing numbers in base 20996011...
Re:6 Megabytes, eh? (1)
JohnPM (163131)  more than 10 years ago  (#7618156)
only 22 bits! For further compression we'd probably have to prove the Riemann hypothesis.
Re:6 Megabytes, eh? (1)
Tackhead (54550)  more than 10 years ago  (#7620337)
Mersenne #40: "Almost one of your base are belong to me!"
gigagilgamesh (0)
eyenot (102141)  more than 10 years ago  (#7614286)
This should be in "YRO" (1, Funny)
stienman (51024)  more than 10 years ago  (#7614296)
Age, DL#, SSN, and even my IP! (19216801)
Obviously it's a thinly veiled ploy to steal my identity! I'ma gonna have to sue the student who found this. Be sure to check if you're in there! Luckily they don't have my credit card numbers, but I bet the next big prime is going to have all that and more.
Be afraid. Be very, very afraid.
Adam
So what (0)
Anonymous Coward  more than 10 years ago  (#7614749)
Re:So what (1)
Kevan_moran (661209)  more than 10 years ago  (#7616933)
IMAM ( I am a mathematician, well ok I got a Maths degree from Trinity Cambridge ( and I di..dn't like Quicksilver (though I did love Cryptonomicon (and I can write Lisp )))).
But should I run the Seti screen saver, the Climate predication model or this one?
My current vote is the CP model but somehow it feels less sexy
(lastStatement.getSounds()==Statements.SOUNDS_GEEK Y ? statement.replace(lastStatement.text(),lastStateme nt.geekFactor()1),lastStatement.text())
Ant deploy
I guess it's time to go home
New name for this? (4, Funny)
dacarr (562277)  more than 10 years ago  (#7614966)
6 million digits can be stored in under 6 megabyte (1)
notyou2 (202944)  more than 10 years ago  (#7615124)
It would be far more efficient to store them in binary coded decimal (BCD, google for it if you don't know what that is), which requires only 4 bits per decimal digit without sacrificing accessibility of the decimal data. In that case it would only take 3 megabytes.
Re:6 million digits can be stored in under 6 megab (1)
iggymanz (596061)  more than 10 years ago  (#7615661)
Re:6 million digits can be stored in under 6 megab (1)
iggymanz (596061)  more than 10 years ago  (#7615670)
Re:6 million digits can be stored in under 6 megab (2, Interesting)
notyou2 (202944)  more than 10 years ago  (#7616636)
On the other hand, the number was probably originally calculated using base2 arithmetic (I'm assuming), so storing in binary might be more natural anyhow.
Re:6 million digits can be stored in under 6 megab (1)
fok (449027)  more than 10 years ago  (#7617201)
Not 6 megabytes, not 2 megabytes ... (0)
Anonymous Coward  more than 10 years ago  (#7616965)
Looks like it takes 13 bytes to express this number.
You can make any number take up a large amount of memory, it just depends on how you write it. The number 2 can take up a gigabyte if you write it with enough 0's after the decimal space. 2.00000000000000000000000000000000000 blah blah you get the idea.
13 bytes. End of story.
mugabytes (2, Funny)
epine (68316)  more than 10 years ago  (#7617631)
How did 21.0 mebibits turn into six megabytes? I think he meant mugabytes.
Offtopic, Inflammatory, Inappropriate, Illegal, or Offensive comments might be moderated, and messages that are too short might be downrated.
You can quote me (1)
Alsee (515537)  more than 10 years ago  (#7617822)

Re:You can quote me (1)
djcapelis (587616)  more than 10 years ago  (#7625210)
1 and 2^20996011  1
Hah!
Re:You can quote me (1)
lordjake (730209)  more than 10 years ago  (#7644614)
Use Base 2^20996011  1 and write it as just 10 (1)
Cerpicio (691827)  more than 10 years ago  (#7618012)
6 Mbytes to represent? I don't think so. (1)
shrikel (535309)  more than 10 years ago  (#7618273)
2^209960111
Quit /.ing their server (1)
RennieScum (118197)  more than 10 years ago  (#7622852)
Dunno...can python handle this? bc? (heh)
Subatomic Particles (2, Interesting)
Kosher Beef Jerky (729463)  more than 10 years ago  (#7625357)
Ever closer (to something infinitely far away) (1)
SamSim (630795)  more than 10 years ago  (#7635268)
Sweet! (1)
mcp33p4n75 (684632)  more than 10 years ago  (#7638272)
Re:Sweet! (1)
lordjake (730209)  more than 10 years ago  (#7644633)