# 42nd Mersenne Prime Probably Discovered

#### Zonk posted more than 9 years ago | from the so-many-digits dept.

369
RTKfan writes *"Chalk up another achievement for distributed computing! MathWorld is reporting that the 42nd, and now-largest, Mersenne Prime has probably been discovered. The number in question is currently being double-checked by George Woltman, organizer of GIMPS (the Great Internet Mersenne Prime Search). If this pans out, GIMPS will have been responsible for the eight current largest Mersenne Primes ever discovered."*

## Uses? (3, Interesting)

## UncleJam (786330) | more than 9 years ago | (#11716881)

Encrypting?

## Re:Uses? (5, Funny)

## selectspec (74651) | more than 9 years ago | (#11716920)

## Re:Uses? (2, Funny)

## kaedemichi255 (834073) | more than 9 years ago | (#11716986)

## Re:Uses? (5, Funny)

## ackthpt (218170) | more than 9 years ago | (#11717013)

Chics dig it.Either that or their eyes glaze over and you sneak a quick peck before they slap you silly.

"ah, l'amour"## Re:Uses? (4, Funny)

## adeyadey (678765) | more than 9 years ago | (#11717130)

## Re:Uses? (3, Funny)

## ArsonSmith (13997) | more than 9 years ago | (#11717141)

## Re:Uses? (1)

## Rei (128717) | more than 9 years ago | (#11717196)

## Re:Uses? (5, Funny)

## Husgaard (858362) | more than 9 years ago | (#11716946)

The theory is that there is an infinite number of these numbers, but they are unlikely to prove the theory by finding them all...

## Re:Uses? (1)

## Mysticalfruit (533341) | more than 9 years ago | (#11717099)

There are an infinite number of numbers hence an infinite number of infinite primes from that set of infinite numbers.

The nice thing was that it only took a billionth of second to figure it all out.

## Re:Uses? (3, Informative)

## Jeremy Erwin (2054) | more than 9 years ago | (#11717063)

And, no, one does not encrypt with Mersenne primes. The rarity of such numbers makes a "brute force" crypto-analysis seem rather plausible. Best to use an ordinary prime number-- there are, after all, many more of them to choose from.

## Re:Uses? (0)

## tehshen (794722) | more than 9 years ago | (#11717064)

I pick two primes, say 3 and 5, and the product of these is 15. A message is encoded using the number 15. If you know the encoded message and the product, you can decrypt it as it only has two factors.

These things take a very long time to do, however, especially with 100-digit primes. And this new one has 33219253 of them, so decrypting could take a while.

## Re:Uses? (0)

## Anonymous Coward | more than 9 years ago | (#11717154)

## Re:Uses? (1)

## tehshen (794722) | more than 9 years ago | (#11717188)

## Re:Uses? (1)

## Husgaard (858362) | more than 9 years ago | (#11717185)

## Re:Uses? (1)

## 26199 (577806) | more than 9 years ago | (#11717194)

Heh... how did this get modded informative? It's no use at all for encryption. Maybe 'funny' would be a better moderation...

## Waste of electricity (-1, Troll)

## Anonymous Coward | more than 9 years ago | (#11716886)

## Of course... (5, Funny)

## rackhamh (217889) | more than 9 years ago | (#11716887)

## Re:Of course... (3, Funny)

## micromoog (206608) | more than 9 years ago | (#11717083)

## Re:Of course... (1)

## captjc (453680) | more than 9 years ago | (#11717090)

## Number Theory Professor... (-1, Offtopic)

## Anonymous Coward | more than 9 years ago | (#11716890)

## Re:Number Theory Professor... (0)

## Anonymous Coward | more than 9 years ago | (#11717027)

## Would a math geek... (-1, Redundant)

## ravenspear (756059) | more than 9 years ago | (#11716892)

## Re:Would a math geek... (4, Informative)

## haluness (219661) | more than 9 years ago | (#11716925)

A Mersenne prime is a Mersenne number, i.e., a number of the form

2^n - 1

that is prime. In order for it to be prime, n must itself be prime.

## Re:Would a math geek... (5, Informative)

## Smallpond (221300) | more than 9 years ago | (#11716928)

## Re:Would a math geek... (4, Informative)

## IvyMike (178408) | more than 9 years ago | (#11716947)

The reason that mersenne primes are usually the biggest is because for primes of this form, there is a primality test (Lucas-Lehmer) that is exceedingly efficient.

## Re:Would a math geek... (1)

## chad.koehler (859648) | more than 9 years ago | (#11716955)

## Re:Would a math geek... (0, Redundant)

## piquadratCH (749309) | more than 9 years ago | (#11716964)

## No, it's not an oxymoron, it's just a regular one (0, Troll)

## Thud457 (234763) | more than 9 years ago | (#11717002)

## Re:Would a math geek... (1)

## em0te (807074) | more than 9 years ago | (#11716990)

One can explain something to another,

but if said person is unable to relate to the way that one is teaching them then either:

The explainer is a

horribleteacher, or, the explainee just simply doesn't understand. And i, for one, am a horrible teacher.Which is why i say:

RTFA## Re:Would a math geek... (1)

## macaulay805 (823467) | more than 9 years ago | (#11717048)

RTFA, it states:Mersenne numbers are numbers of the form Mn = 2n - 1. For example, M7 = 27 - 1 = 127 is a Mersenne number. In fact, since 127 is also prime, 127 is also a Mersenne prime.That was a cut-and-paste job btw.

## The real magic number (0)

## Anonymous Coward | more than 9 years ago | (#11716896)

## first fart (-1, Troll)

## Anonymous Coward | more than 9 years ago | (#11716899)

## Could it be? (0)

## Anonymous Coward | more than 9 years ago | (#11716900)

## good website for info (-1, Redundant)

## EaterOfDog (759681) | more than 9 years ago | (#11716907)

## That website... (0, Redundant)

## daveschroeder (516195) | more than 9 years ago | (#11716938)

in the summary.(Last sentence, "Mersenne Primes".)

Sheesh.

## Re:good website for info (0, Flamebait)

## Rosco P. Coltrane (209368) | more than 9 years ago | (#11716963)

Mods these days couldn't see a karma-whore if it painted his bottom blue, put on a jester's hat and shouted "I'm a karma-whore"...

## Re:good website for info (0, Offtopic)

## EaterOfDog (759681) | more than 9 years ago | (#11716982)

## wolfram.com? (0)

## Anonymous Coward | more than 9 years ago | (#11717085)

## I never thought I'd say this... (0)

## Paladin144 (676391) | more than 9 years ago | (#11716911)

## You just know... (0)

## Anonymous Coward | more than 9 years ago | (#11716917)

If this pans out, GIMPS will have been responsible for the eight current largest Mersenne Primes ever discovered.Being able to say that sentence was the reason they named the project the way they did.

## Great. Now what is it??????? (1, Funny)

## solafide (845228) | more than 9 years ago | (#11716918)

Congratulations George! Now what use is this? In cryptology? But how?

## Re:Great. Now what is it??????? (0, Offtopic)

## ravenspear (756059) | more than 9 years ago | (#11716954)

Tell us what it is!!!Would you like that in decimal or binary?

## Re:Great. Now what is it??????? (3, Funny)

## Anonymous Coward | more than 9 years ago | (#11717008)

11111...1111

where "..." means some number of 1s.

## Re:Great. Now what is it??????? (2, Funny)

## ArsonSmith (13997) | more than 9 years ago | (#11717082)

## Re:Great. Now what is it??????? (0)

## Anonymous Coward | more than 9 years ago | (#11717107)

## Re:Great. Now what is it??????? (1)

## ArsonSmith (13997) | more than 9 years ago | (#11717176)

## Can Inkscape be used to discover primes? (-1, Offtopic)

## Anonymous Coward | more than 9 years ago | (#11716926)

## Sheesh (2, Funny)

## Anonymous Coward | more than 9 years ago | (#11716927)

The number in question is currently being double-checked by George Woltman, organizer of GIMPSAnd while George takes time off to double-check Mersenne primes, GIMP doesn't get any closer to the usability of Photoshop...

## OT but I'll bite.. (0, Offtopic)

## MikeFM (12491) | more than 9 years ago | (#11717183)

## If I do say so myself. (1, Funny)

## Anonymous Coward | more than 9 years ago | (#11716935)

## Re:If I do say so myself. (1)

## yogikoudou (806237) | more than 9 years ago | (#11717015)

## Re:If I do say so myself. (2, Funny)

## cyriustek (851451) | more than 9 years ago | (#11717053)

## Re:If I do say so myself. (0)

## Anonymous Coward | more than 9 years ago | (#11717078)

## Practical Applications/Uses? (4, Insightful)

## NitroWolf (72977) | more than 9 years ago | (#11716937)

## Re:Practical Applications/Uses? (2, Informative)

## mctk (840035) | more than 9 years ago | (#11717103)

## Re:Practical Applications/Uses? (3, Informative)

## robbyjo (315601) | more than 9 years ago | (#11717106)

From here [haugk.co.uk] :

Finding new Mersenne primes is not likely to be of any immediate practical value. This search is primarily a recreational pursuit. However, the search for Mersenne primes has proved useful in development of new algorithms, testing computer hardware, and interesting young students in math.## Re:Practical Applications/Uses? (5, Informative)

## vivin (671928) | more than 9 years ago | (#11717109)

Also, necessity is the mother of invention. Even if Big Primes aren't really a necessity, it has brought forth some really innovative algorithms and methods to finding prime numbers. Furthermore, it has developed newer and faster ways for multiplying integers.

In 1968, Strassen figured out how to multiply integers quickly by using Fast Fourier Transforms. Strassen, along with Schönhage improved on the method and published a refined version in 1971. GIMPS now uses an improved version of their algorithm. This improved version was developed by Richard Crandall (a longtime researcher of Mersenne Primes).

Another application of finding Prime Numbers is to test computer hardware. Since testing Primes involves a thorough excercise of basic mathematical operations, it provides a good test for hardware. Software routines from GIMPS were used by Intel to test the PII and the Pentium Pro chips before they were shipped. The search for prime numbers was also indirectly responsible for the discovery of the infamous FDIV bug on the Pentium, during the calculation of the twin prime constant (by Thomas Nicely).

## Re:Practical Applications/Uses? (3, Funny)

## myowntrueself (607117) | more than 9 years ago | (#11717203)

## Re:Practical Applications/Uses? (3, Interesting)

## Sloppyjoes7 (556803) | more than 9 years ago | (#11717168)

Whatever the case, this must be a more useful application for CPU power than Seti@home, which is a total waste of energy. Literally.

What we need are more projects that use distributed computing for useful calculations that could further science or solve problems. Universities build giant supercomputers to help their students calculate equations and solve problems. Maybe the students should release the problems over a network, and have home users calculate the answer for them. It'd save the Universities a lot of money.

I don't think it would work for code cracking, or government projects, as these contain sensitive information.

## Re:Practical Applications/Uses? (3, Insightful)

## pclminion (145572) | more than 9 years ago | (#11717192)

Can someone explain what the application/use these primes are for?Communicating with alien species, perhaps.

Mersenne primes have two interesting properties that might catch the attention of alien species: when written in binary, they are entirely composed of '1' bits; and, of course, they are prime.

A sure way to prove to another being that you are intelligent is to spew a bunch of numbers which all happen to be prime. The fact that they can be tranmitted using only '1' bits means the modulation is simple -- just send a series of pulses.

## A Mersenne Prime is... (4, Informative)

## vivin (671928) | more than 9 years ago | (#11716959)

Mn = 2^n - 1.

Mersenne primes have a connection with Perfect Numbers (numbers that are equal to the sum of their proper divisors) where by if M is a Mersenne prime, then M(M+1)/2 is a perfect number.

## Re:A Mersenne Prime is... (1)

## ch-chuck (9622) | more than 9 years ago | (#11717180)

## Mersenne Primes? Bah! (5, Funny)

## Guano_Jim (157555) | more than 9 years ago | (#11716980)

## Mersenne Primes - Definition (2, Informative)

## Un-Thesis (700342) | more than 9 years ago | (#11716984)

## Re:Mersenne Primes - Definition (1)

## omahajim (723760) | more than 9 years ago | (#11717020)

## Re:Mersenne Primes - Definition (1)

## omahajim (723760) | more than 9 years ago | (#11717045)

## Re:Mersenne Primes - Definition (4, Insightful)

## jandrese (485) | more than 9 years ago | (#11717051)

## Re:Mersenne Primes - Definition (1, Informative)

## Anonymous Coward | more than 9 years ago | (#11717111)

A Mersenne Prime is where the prime number also fulfills the equation 2^P - 1 2^2 - 1 = 3 ... 3 is a mersenne prime. 2^3 - 1 = 5 ... 5 is a mersenne prime. 2^4 - 1 = 7 ... 7 is a mersenne prime.Were you up late last night or something? 2^3 - 1 is NOT 5. 5 is NOT a Mersenne prime. 2^4 - 1 is NOT 7. 7

isa Mersenne prime, though. You suck at math.## Re:Mersenne Primes - Definition (0)

## Anonymous Coward | more than 9 years ago | (#11717145)

2^4=16 therefore 2^4 -1 = 15 not 7, 15 isn't prime

## Probably silly reference (4, Funny)

## serutan (259622) | more than 9 years ago | (#11716985)

Lord Percy: "The King is dead! L-"

Prince Harry [interrupting]: "

Probablydead."Lord Percy: "The King is probably dead!"

## Spoiler alert about the number (4, Funny)

## Anonymous Coward | more than 9 years ago | (#11716995)

Seriously, don't reead any farther....

It only has

twofactors.## Immoral use of computing power (0, Flamebait)

## Space_Soldier (628825) | more than 9 years ago | (#11716998)

## Re:Immoral use of computing power (5, Funny)

## Stanistani (808333) | more than 9 years ago | (#11717047)

Because of course aliens will feed us...

They even will bring a cookbook with them, "To Serve Mankind."

## Re:Immoral use of computing power (1)

## JustNiz (692889) | more than 9 years ago | (#11717055)

## Re:Immoral use of computing power (0)

## Anonymous Coward | more than 9 years ago | (#11717066)

## Screw you AC (1)

## Mr Guy (547690) | more than 9 years ago | (#11717132)

amgoing to eat them.## Re:Immoral use of computing power (0)

## Anonymous Coward | more than 9 years ago | (#11717112)

If someone buy the computing power to discover new primes it's their right to do so.

## Re:Immoral use of computing power (2, Funny)

## redivider (786620) | more than 9 years ago | (#11717125)

## Re:Immoral use of computing power (1)

## mctk (840035) | more than 9 years ago | (#11717150)

## Re:Immoral use of computing power (0)

## Anonymous Coward | more than 9 years ago | (#11717159)

If you're going for one of the tried-and-tested classic Slashdot trolls, please stick to the script.

## Re:Immoral use of computing power (1)

## GIL_Dude (850471) | more than 9 years ago | (#11717199)

## Woohoo! The world is saved! (1, Funny)

## kakos (610660) | more than 9 years ago | (#11717028)

Thank you Great Internet Mersenne Prime Search!

## Can't see the pattern? (2, Funny)

## nitio (825314) | more than 9 years ago | (#11717086)

42nd Mersenne Prime...## One practical use of Mersenne Primes... (5, Interesting)

## William_Lee (834197) | more than 9 years ago | (#11717036)

Prime95 (which searches for these primes) really puts a load on the CPU and raises the temperature in a hurry. It's commonly used to test the stability of overclocking configurations since it stresses the chip and is able to detect if there is an error in the computation.

Generally, if you can run Prime95 for 24 hours straight, most people will consider the overclocked PC a stable configuration.

## Client written in assembler (0)

## Anonymous Coward | more than 9 years ago | (#11717040)

## Yes! (5, Funny)

## Anonymous Coward | more than 9 years ago | (#11717054)

If this pans out, GIMPS will have been responsible for the eight current largest Mersenne Primes ever discovered.In your face, Photoshop!

## And??? (0, Redundant)

## michelcultivo (524114) | more than 9 years ago | (#11717070)

## Two unknowns (5, Informative)

## MaGogue (859961) | more than 9 years ago | (#11717076)

This has not yet been confirmed, therefore there could be less than 42 known Mersenne primes.

Hovewer, according to MathWorld, there is a chance that it is not the 42nd Mersenne prime at all for another reason

"However, note that the region between the 39th and 40th known Mersenne primes has not been completely searched, so it is not known if M20,996,011 is actually the 40th Mersenne prime.."Looks like the big math guys don't exactly know how to count at all

## That brings back some memories... (5, Interesting)

## Anonymous Coward | more than 9 years ago | (#11717077)

As part of the course, we studied Mersenne primes. At the time, I was dabbling in x86 assembler, and I decided to write a program to calculate the then largest known Mersenne prime number: 2^31 - 1, which worked out to 65,050 digits.

The size worked out perfectly, as in 1989 that meant it could fit into one 65KB segment on my blazing-fast 8Mhz 8088. As I recall, the runtime was about two days. The program still works--I can't remember how long it took to run on a 3Ghz P4, but I think it was just a few minutes.

I'm sure any competent programmer (read--not me) could calculate the result much faster, but at the time I was very proud of my little creation.

## Re:That brings back some memories... (4, Informative)

## djmurdoch (306849) | more than 9 years ago | (#11717201)

As part of the course, we studied Mersenne primes. At the time, I was dabbling in x86 assembler, and I decided to write a program to calculate the then largest known Mersenne prime number: 2^31 - 1, which worked out to 65,050 digits.I don't think it actually did bring back those memories. 2^31-1 is 2147483647. You're thinking of Mersenne prime 31, which is 2^216091 - 1.

## ok now , back to protien folding! (2)

## L1nux_L0ser83 (860647) | more than 9 years ago | (#11717092)

im a geek...but damn...thats uber-geekish

## the trouble is (3, Funny)

## pmike_bauer (763028) | more than 9 years ago | (#11717105)

The number in question is currently being double-checked by George WoltmanOk...lets see here...

5465875133124687545551258898456556......9803480

2BUMMER!

## What an incredibly awesome... (3, Insightful)

## GatesGhost (850912) | more than 9 years ago | (#11717113)

## When will this be put into SSH or MUTE? (0)

## Anonymous Coward | more than 9 years ago | (#11717124)

## OMG! Do you know what this means!?!?! (2, Funny)

## Eskimore_ (842733) | more than 9 years ago | (#11717135)

.

.

No really, please tell me. I haven't a clue...

## 42? gimp? (1)

## Esine (809139) | more than 9 years ago | (#11717164)

## Here's one good reason... (3, Interesting)

## thesatch (844290) | more than 9 years ago | (#11717174)

Thought it takes my 1.7Ghz 3 months to test a 10mil digit prime.

## Something`s wrong... (1)

## Anonymous Coward | more than 9 years ago | (#11717186)

Something`s wrong here

## You ask why? (1)

## SafteyMan (860733) | more than 9 years ago | (#11717187)

## Use (0)

## northcat (827059) | more than 9 years ago | (#11717191)