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o(1) statistical prime approximation
(thelemmy.club)
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this post was submitted on 22 Feb 2026
850 points (99.1% liked)
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If you scaled it based on the size of the integer you could get that up to 99.9% test accuracy. Like if it's less than 10 give it 50% odds of returning false, if it's under 50 give it 10% odds, otherwise return false.
That would make it less accurate. It's much more likely to return true on not a prime than a prime
Correct. Not are why people are upvoting. If 10% of numbers are prime in a range, and you always guess false, you get 90% right. If you randomly guess true 10% of the time, you get ~80% right.
More random means more towards 50% correctness.
And 2,3,5,7 are primes of the first numbers, making always false 60% correct and random chance 50%
Code proof or it didn't happen.
Extra credit for doing it in Ruby
Now you're thinking with ~~portals~~ primes!
Makes me wonder where the actual break even would be. Like how long does making one random number take versus sins lookups. Fuck it, do it in parallel. Fastest wins.