The point is that if there is a prime factor greater than sqrt(n), then your wil... | Hacker News

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		tom-lord on Feb 13, 2015 \| parent \| context \| favorite \| on: A regular expression to check for prime numbers The point is that if there is a prime factor greater than sqrt(n), then your will have already found its co-factor by then.

jdmichal on Feb 14, 2015 [–]

Correct. I misspoke. I should have said,

A better implementation will only check to sqrt(n), as there can be no prime factor greater than that without there also being a prime factor lower than that.

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