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Math Science

47th Mersenne Prime Confirmed 89

radiot88 writes to let us know that he heard a confirmation of the discovery of the 47th known Mersenne Prime on NPR's Science Friday (audio here). The new prime, 2^42,643,801 - 1, is actually smaller than the one discovered previously. It was "found by Odd Magnar Strindmo from Melhus, Norway. This prime is the second largest known prime number, a 'mere' 141,125 digits smaller than the Mersenne prime found last August. Odd is an IT professional whose computers have been working with GIMPS since 1996 testing over 1,400 candidates. This calculation took 29 days on a 3.0 GHz Intel Core2 processor. The prime was independently verified June 12th by Tony Reix of Bull SAS in Grenoble, France..."
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47th Mersenne Prime Confirmed

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  • Odd's prime (Score:5, Funny)

    by fph il quozientatore ( 971015 ) on Saturday June 13, 2009 @07:06PM (#28323155)
    So, all primes greater than two are odd, but only one of them is Odd's!
    • Re: (Score:1, Funny)

      by Snarf You ( 1285360 )
      I wonder what the odds were that he actually found it?
    • Re: (Score:2, Funny)

      by Melkman ( 82959 )
      That's odd when you think about it.
    • by bcrowell ( 177657 ) on Saturday June 13, 2009 @08:18PM (#28323575) Homepage
      His brother, Even Magnar Strindmo, is also an IT professional. Even, like his brother Odd, has been testing candidates since 1996. The latest candidate in Even's search was 2^42,643,801-2, which was found to be composite. The very next number, 2^42,643,801-1, was the one his brother found to be prime. "Yeah, it kind of hurts to get so close and not be the one who got it," admits Even, "but I gave it my best game. We agreed back in '96 that we'd split up the work and go even-odd. I guess it was just a matter of luck that he got the first prime. I'm going to keep on trying, though. He's ahead now, 1-0, but if we keep going, I figure at some point I'll pull ahead."
      • Re: (Score:1, Interesting)

        by Anonymous Coward

        Hah, excellent. :)

        (For the non-locals, Even is a perfectly common Norwegian name.)

  • by tqft ( 619476 ) <> on Saturday June 13, 2009 @07:24PM (#28323255) Homepage Journal

    The admins missed the prime for about a month []
    Apparently the email that was supposed to be sent wasn't when the prime was reported

    • The code has been tested, as this is not the first prime numbers this project finds (far from it in fact).

      Apparently it hasn't been tested enough though ;)

  • by moon3 ( 1530265 ) on Saturday June 13, 2009 @07:33PM (#28323313)
    Discovering a prime number that distant from the zero is like discovering a Pluto like planet in outer space. But instead of Hubble telescope you need a powerful mathematical one..
  • Hmm (Score:4, Informative)

    by Anenome ( 1250374 ) on Saturday June 13, 2009 @07:36PM (#28323335)

    I honestly forget why I'm supposed to care about Mersenne primes. Like, I read something about them awhile back, it was somewhat interesting... and then--yeah. So: []
    In mathematics, a Mersenne number is a positive integer that is one less than a power of two.

    A Mersenne prime is a Mersenne number that is prime. As of June 2009[ref], only 47 Mersenne primes are known; the largest known prime number (243,112,609 1) is a Mersenne prime, and in modern times, the largest known prime has almost always been a Mersenne prime.[1] Like several previously-discovered Mersenne primes, it was discovered by a distributed computing project on the Internet, known as the Great Internet Mersenne Prime Search (GIMPS). It was the first known prime number with more than 10 million base-10 digits.

    For those who can't even remember what a prime is, it's a number that can only be divided (evenly) by 1 and itself. Here's a list of the first primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97

    The Mersenne primes are the largest known primes.

    Prime numbers have applications in electronic security and encryption breaking. I'm not sure what other purpose there is to knowing them, other than knowing them. The Mersenne in particular seem to be merely mathematical curiosities right now.

    I was much more excited by the discovery that the the Fibonnacci sequence is contained within the 1/89 calculation. []

    • by JoshuaZ ( 1134087 ) on Saturday June 13, 2009 @08:03PM (#28323485) Homepage
      The historical reasons for caring about Mersenne Prime are twofold: First, Mersenne primes correspond to perfect numbers (numbers that are the sum of their positive less than the number. So for example, 6 has as proper divisors 1,2 and 3 and 1+2+3=6). The ancient Greeks were fascinated by perfect numbers but could not do much to understand them. Euclid showed that if one had a Mersenne prime one can construct an even perfect number. In particular, if 2^n-1 is prime then (2^n-1)*2^(n-1) is perfect. Almost 2000 years later, Euler showed that every even perfect number is of Euclid's form. Thus, investigating Mersenne primes tells us more about perfect numbers. The oldest unsolved problems in math are 1) are there any odd perfect numbers? and 2) are there infinitely many even perfect numbers? Thus, investigating Mersenne primes helps us get closer to solving one of the two oldest unsolved problems in mathematics.
      • by Anonymous Coward

        Well, I hate to break it to you, but you won't find any odd perfect numbers by finding Mersenne primes. (2^n-1)*2^(n-1) is going to be even for all n > 1.

        • Well, I hate to break it to you, but you won't find any odd perfect numbers by finding Mersenne primes. (2^n-1)*2^(n-1) is going to be even for all n > 1.

          You missed that part where every even perfect number is of that form. It says nothing about what form odd perfect numbers take, if they exist at all.

      • Re: (Score:3, Insightful)

        by Anenome ( 1250374 )

        Well, they may be unsolved problems, but again, they look like they have no relevance to anything, no application, other than being unanswered questions. But, like so many things, knowledge is valuable for its own sake, and who knows what revolution may result from what is now just a mathematical curiosity. Stealth-flight technology was originally harvested from a little known paper on radar written by an obscure Russian scientist. Kind of ironic that we were the ones to develop it. What you're really talki

    • Re: (Score:2, Interesting)

      Actually, you can apparently use larger Mersenne Primes to improve results in totally different but very useful fields, like privacy-related schemes. For example, this paper [] uses large Mersenne primes to get interesting results on Locally Decodable Codes and Private Information Retrieval Schemes...
  • My calculator doesn't show it, anyone have the value of the prime?
  • Well I don't know why it took 29 days for the computer to tell him it was so, wolfram alpha told me it was prime in ~1 second. []

    On that note, I asked Wolfram the other day the tree in a forest thing and I finally have an answer! []

    • by chill ( 34294 )

      Really? I don't see where it generates output.

      Change the last digit of the power to a 0 and it quickly comes up with FALSE, but I never see a "TRUE" for the original question. Where is the answer?

      • That funny E sign means 'element of a set' [] and the set is defined by that funny P sign, which means all primes. This means that Wolfram is saying that 2^42643792 -1 is a member of the set of prime numbers. See also how they know it is a prime. []
        • by chill ( 34294 )

          Yes, I know that. :-)

          What I'm saying is that is listed under "input". That indicates to me it was reformulating your English question into a proper mathematical statement. Nowhere do I see output.

          Try it this way and you'll see what I'm looking for: []

          The "input" statement is the same formulation, but there is now a "result" block which was missing from your query. That result states "False" as opposed to changing the element

          • Here is a result which says true:


            I guess it knows (2^n-1) can only be a prime number if n is prime (that's a known theorem).

            • by chill ( 34294 )

              Thanks. That leads me to believe it didn't really do the original calculation, instead it just gave up quietly.

              Of course, they could always "cheat". They could create a list of known Mersenne Primes and just check against that...

              • It probably has a bunch of quick checks that can tell it "definitely not prime", "definitely prime" or just give up if none of the heuristics applies.

                One of the checks they could add is the one you mentioned (a list of the known ones).

                • Ah I see what you are saying now, and you are rbarreira is probably right, it has given up. I thought that the input region saying it was a member meant it was true... Oh well, I did think it was pretty impressive that it new so quick!
                  • Ah I see what you are saying now, and you are rbarreira is probably right, it has given up. I thought that the input region saying it was a member meant it was true... Oh well, I did think it was pretty impressive that it new so quick!

                    I meant "knew so quick".

                  • it has given up

                    Maybe if you gave it a month or two it would get back to you eventually ;)

              • At this moment they still have not confirmed the 47th Mersenne prime in Alpha: 47th Mersenne prime []

                Further more, the 41st-46th primes are listed as conjectured.

                If we consider the 40th Mersenne prime, 2^20996011-1 [] it gives the same result when checking its primeness (times out) [].
  • ... the Great Old Ones will return, all life on earth will be destroyed.
    • Re: (Score:1, Funny)

      by Anonymous Coward

      .. the Great Old Ones will return, all life on earth will be destroyed.

      Oh, come on, Biden isn't that bad.

  • According to the The Hitchhiker's Guide to the Galaxy, "Odd Magnar Strindmo" was a fourth generation accounting prefect on the third major planet of the second solar system in the first minor galactic cluster directly to the "left" of the vicinity of Betelgeuse - a star that has recently gone supernova. After achieving a modicum of fame for discovering the 47th known Mersenne Prime, during extended holiday on the, mostly harmless, planet named Earth, Mr Strindmo retired to a life of semi-luxury where he pr
  • I say the entire number was photoshopped.
  • The link on the GIMPS home page [] points to where one may obtain the decimal digits of the new Mersenne Prime []. Other forms of this prime are available []:

    The dashed form of the English name i

Marriage is the sole cause of divorce.