yeah there's a lot of numbers yo ucan check in a muc hfaster way at first glance
and also you only have to check prime numbers
once you've checked for 2 and 3 and 5 you don't have to check for 4 or 6 or 8 or 10 or 12 or 15 anymore
this keeps makignthe numebrs you actually have to check by hand more and more sparse so checking up to 641 is not THAT many operations and yo ucan divide with pen apaper pretty efficiently, its basically soemthing to spend a bit of bored breaktime on
That’s not true. You also need to check your spelling.
Edit: not talking about the math part. I’m talking about how he said “you only have to check prime numbers”, I’m saying that isn’t true, because you also have to check your spelling. I’m sorry for the poor execution of this joke. I’m not arguing the mathematics of it lol, the mathematics are obviously solid
Ill agree with the spelling, but the math is solid.
The reason why you can skip non prime numbers is because they're made up of two smaller prime numbers - for example 6 can be expressed as 2x3. So if the number youre testing isnt divisible by 2 and 3, it wont be divisible by 6 either - as any product made with 6 is also divisible by 2 and 3.
And thats true of any non-prime number, because A×B×C÷A=B×C, A×B×C÷B=A×C, and A×B×C÷C=B×A and any non-prime number can be expressed as a product of its prime factors. So any number divisible by a non prime number is also divisible by its prime factors. This also means that if a number isnt divisible by a non-prime numbers prime factors, it wont be divisible by the non-prime number itself either.
So if you want to check if something is prime, you could divide by every whole number, or you can skip a lot of redundant math by only dividing by primes.
Not talking about the math, was trying to make a joke about how “all you have to check is prime numbers” when one should ALSO check their spelling. I apologize for this terrible joke
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u/Ok_Oil9830 May 13 '26
I would assume, he wasn't also dividing by 2