How to determine if a large number is prime? Is this True?

ONeil · 2020-12-12, 05:16

Is the below statement True?

Quote:

You check every prime number that's less than the square root of the number you're concerned with. The square root of 941 is 30.67, so check every prime number up to 29. If none of them divide 941, then it is prime.
https://www.reddit.com/r/learnmath/c...mber_is_prime/

CRGreathouse · 2020-12-12, 05:25

Less than or equal to, yes. (The bold part is necessary in case you encounter the square of a prime.) But this is a very slow method and much better ones are known even for quite small numbers.

kriesel · 2020-12-13, 13:35

https://brilliant.org/wiki/prime-testing/
https://tutorialspoint.dev/algorithm...primality-test
easily found with https://duckduckgo.com/?t=ffnt&q=pri...ing+aks&ia=web

2020-12-13, 13:35	#3
kriesel "TF79LL86GIMPS96gpu17" Mar 2017 US midwest 37×131 Posts	https://brilliant.org/wiki/prime-testing/ https://tutorialspoint.dev/algorithm...primality-test easily found with https://duckduckgo.com/?t=ffnt&q=pri...ing+aks&ia=web Last fiddled with by kriesel on 2020-12-13 at 13:38

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2020-12-12, 05:25	#2
CRGreathouse Aug 2006 3·1,987 Posts	Less than or equal to, yes. (The bold part is necessary in case you encounter the square of a prime.) But this is a very slow method and much better ones are known even for quite small numbers.