40th Mersenne Prime Found 99
Posted
by
michael
from the primalurges dept.
from the primalurges dept.
FenwayFrank 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 (Score:5, Funny)
Wait, no, it just got slashdotted before it fully loaded...
Re:Fraud (Score:2, Informative)
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 (Score:3, Funny)
Re:interesting (Score:1)
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 (Score:2)
Sure we do! [wikipedia.org]
BTW, Remember me? :)
Finally! (Score:5, Funny)
Efficient factoring algorithm (Score:1)
Re:Finally! (Score:1)
Re:Finally! (Score:2)
ObTiredOldJoke (Score:1, Redundant)
Here's something stupid to do. (Score:5, Funny)
I wonder who has the most occurrences.
Re:Here's something stupid to do. (Score:4, Insightful)
Re:Here's something stupid to do. (Score:1)
Re:Here's something stupid to do. (Score:2)
Daniel
Re:Here's something stupid to do. (Score:2)
Re:Here's something stupid to do. (Score:2)
Re:Here's something stupid to do. (Score:2)
Re:Here's something stupid to do. (Score:1)
Re:Here's something stupid to do. (Score:1)
Re:Here's something stupid to do. (Score:2)
Re:Here's something stupid to do. (Score:3, Informative)
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 (Score:3, Funny)
Wow! (Score:4, Funny)
Hah, you really thought I actually counted for a second there!
Re:Wow! (Score:1)
Get it straight leetboy.
40th? (Score:5, Insightful)
Time to update all pages (Score:4, Informative)
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! (Score:5, Funny)
Re:Awesome! (Score:1)
math == piracy (Score:3, Funny)
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!
Re:not prime (Score:1)
with one exception
Re:not prime (Score:1)
Any expression
2^n
where n is a positive integer will be even,
and subtracting 1 will make it odd.
Re:not prime (Score:2)
So effectively you are doing 2 XOR 3  1 = 1  1 = 0
Re:not prime (Score:1)
(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... (Score:5, Informative)
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.
Damn them! (Score:1, Funny)
Re:Damn them! (Score:2)
Re:Damn them! (Score:1)
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! (Score:1)
Hey! That's the combination on my luggage!
If I post the number here... (Score:3, Funny)
6 Megabytes?????? (Score:1, Troll)
This number takes more like 21 KB to represent.
Re:6 Megabytes?????? (Score:2)
Ster
Re:6 Megabytes?????? (Score:2)
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?????? (Score:2)
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?????? (Score:1)
Re:6 Megabytes?????? (Score:1)
Re:6 Megabytes?????? (Score:2)
Hmm (Score:1)
Xbox? (Score:2)
(joke)
6 Megabytes, eh? (Score:3, Informative)
This is all perfectly true, modulo an arithmetic error on my part.
Re:6 Megabytes, eh? (Score:3, Informative)
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? (Score:1)
Re:6 Megabytes, eh? (Score:2)
It's not the most compact form, to be sure, but it is, as advertised, 6 megabytes of primey goodness.
Re:6 Megabytes, eh? (Score:1)
Re:6 Megabytes, eh? (Score:2)
Re:6 Megabytes, eh? (Score:2)
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? (Score:2)
Re:6 Megabytes, eh? (Score:1)
And if someone brings up storing numbers in base 20996011...
Re:6 Megabytes, eh? (Score:2)
only 22 bits! For further compression we'd probably have to prove the Riemann hypothesis.
Re:6 Megabytes, eh? (Score:2)
Mersenne #40: "Almost one of your base are belong to me!"
This should be in "YRO" (Score:2, Funny)
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
Re:So what (Score:1)
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_GEE K Y ? statement.replace(lastStatement
New name for this? (Score:5, Funny)
6 million digits can be stored in under 6 megabyte (Score:1)
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 (Score:2)
Re:6 million digits can be stored in under 6 megab (Score:2)
Re:6 million digits can be stored in under 6 megab (Score:2, Interesting)
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 (Score:1)
mugabytes (Score:3, Funny)
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 (Score:2)

Re:You can quote me (Score:1)
1 and 2^20996011  1
Hah!
Re:You can quote me (Score:1)
Use Base 2^20996011  1 and write it as just 10 (Score:1)
6 Mbytes to represent? I don't think so. (Score:2)
2^209960111
Quit /.ing their server (Score:2)
Dunno...can python handle this? bc? (heh)
Subatomic Particles (Score:2, Interesting)
Ever closer (to something infinitely far away) (Score:1)
Sweet! (Score:1)
Re:Sweet! (Score:1)