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Old 2020-12-12, 05:16   #1
Dec 2017

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

Is the below statement True?

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.
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Old 2020-12-12, 05:25   #2
CRGreathouse's Avatar
Aug 2006

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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.
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Old 2020-12-13, 13:35   #3
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easily found with

Last fiddled with by kriesel on 2020-12-13 at 13:38
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