20200513, 08:24  #1 
"murat"
May 2020
turkey
3×29 Posts 
checking big digit number as prime
which one is hard . calculating big digit number or checking it . which methods ca be use for checkig numbers ?
MODERATOR NOTE: Thread moved from FermatSearch forum Last fiddled with by Dr Sardonicus on 20200513 at 13:17 Reason: Note that thread was moved 
20200513, 13:40  #2 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
3·5^{5} Posts 
Are you asking how hard it is to take 2^{332,199,893}1 and expand it to its full decimal form vs checking it to see if it is prime?
The first is very fast. Faster than the old machines could display it. The second is slow. If you have some complex formula to calculate the number vs checking it to see if it is prime, even that, calculating the number is faster than checking it (in almost every case). 
20200513, 14:29  #3  
Sep 2002
Database er0rr
2×3×599 Posts 
Quote:
Last fiddled with by paulunderwood on 20200513 at 14:32 

20200513, 17:25  #4 
"Curtis"
Feb 2005
Riverside, CA
11105_{8} Posts 
As for "which methods" from the OP question it depends on the form that describes your number, as well as how big "big digits" is.
Give us more info about what size and what form you have in mind, you'll get a better answer. 
20200513, 17:49  #5 
"murat"
May 2020
turkey
87_{10} Posts 
I think I am at the begining . :) I get 2^50.000 at first night with my own code . can we think it is big :) . I am recording all results from 2 ^ 1 to 2 ^ 50000 . and it goes on I want to calculate fermat and mersenne primes
Last fiddled with by drmurat on 20200513 at 17:55 
20200513, 18:03  #6  
Sep 2002
Database er0rr
2×3×599 Posts 
Quote:
Code:
gettime();write("delMe",2^50000+1);gettime() 1 Last fiddled with by paulunderwood on 20200513 at 18:05 

20200513, 18:15  #7 
"murat"
May 2020
turkey
3·29 Posts 
I am calculating 2^50000 and writing to file and calcupating 2^50001 and ... goes on . I get 2^60000 . big numbers get years and years ...

20200513, 18:20  #8 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
3×5^{5} Posts 
Apfloat also works nice: http://www.apfloat.org/apfloat/
Also http://numcalc.com/ handles it quickly And 2^500001 is not prime. The exponent has to be prime. Last fiddled with by Uncwilly on 20200513 at 18:21 
20200513, 18:29  #9 
"murat"
May 2020
turkey
1010111_{2} Posts 
thank you . it will be so helpfull to me . I get 2 ^ 65000

20200513, 18:36  #10 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
249F_{16} Posts 
What are your plans (please use a paragraph to state it)? If you are just practicing your coding, look at places that can help you learn. If you don't trust what everyone else has done, you have issues. Are you testing the numbers using LL? Or are you doing it via a more rudimentary way? What language/platform are you using? Why do you want the decimal expansion?

20200513, 18:48  #11 
"murat"
May 2020
turkey
3·29 Posts 
okay . I am not plannig to improve my coding . I am behind so many thing about primes . I am medical doctor . I know a bit coding . and intrested in with primes nearly 20 mounths .I do my calculations with my own . it has to reason fitst when I need data fot one process . getting whole data is hard . you must open so many zip files . make them as you want . it gets so time . the second reason making calculation with your own gives you a chance of oservation . I am asking here to calculating 2 ^70000 is hard . I realy dont know the answer .

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