question and answer thread.

Quote:

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Originally posted by Simon666

It only means that not both numbers at the same time can be prime.

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Of course, sorry. That's what I meant.

are the numbers 2 and 9

tell me if they are and i'll explain why

2 and 9 are not correct

Quote:

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Originally posted by Elrond
2 and 9 are not correct

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can one of the numbers be 2

Quote:

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Originally posted by SeventhStar

can one of the numbers be 2

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@SeventhStar: based on your strategy, I have worked out an algorithm which should work:

Code:

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for(int a = 2; a <= 100; a++)
{
  for(int b = 2; b <= 100; b++)
  {
    AskElrondIfCanBe(a,b);
  }
}

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:D :D :D

Quote:

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Originally posted by gstercken


@SeventhStar: based on your strategy, I have worked out an algorithm which should work:

Code:

---

for(int a = 2; a <= 100; a++)
{
  for(int b = 2; b <= 100; b++)
  {
    AskElrondIfCanBe(a,b);
  }
}

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:D :D :D

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Nope i thought of a great idea but the promlem is that if one of the nubers can be 2 i have too much answers

PS. you can remove these '{}' thingies

I have an even more efficient one:

Code:

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for(int a = 2; a <= 100; a++)
{
  for(int b = a+1; b <= 100; b++)
  {
    AskElrondIfCanBe(a,b);
  }
}

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:D:D:D

Quote:

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Originally posted by Simon666
I have an even more efficient one:

Code:

---

for(int a = 2; a <= 100; a++)
{
  for(int b = a+1; b <= 100; b++)
  {
    AskElrondIfCanBe(a,b);
  }
}

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:D:D:D

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Solve first, optimize later! :D

Quote:

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Originally posted by SeventhStar
PS. you can remove these '{}' thingies

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I like them. They keep the code much cleaner, IMHO. ;)

Quote:

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P. : "I can't find these numbers"

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Commentary: P thinks Hmmm... I know the sum is 24, but that means the numbers could be (2,12), (3,8), or (4,6).

Quote:

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S. : "I knew it"

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Commentary: S thinks Well of course he can't know it... since the sum is 11, the numbers could be (2,9), (3,8), (4,7), or (5,6). For each possibility, the product could be made from more than one possibility. For example, if it's (2,9), Mr. P would know the product is 18, meaning the numbers could be (2,9) or (3,6).

Quote:

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P. : "Then I have know what they are !"

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Commentary: P thinks If the numbers were (2,12) then S couldn't have known that, because the sum is 14 so the numbers could have been (3,11), and their product can only be factored one way. If the numbers were (4,6) then S again couldn't have known that, because the sum is 10 so the numbers could have been (3,7), and their product can only be factored one way. If the numbers were (3,8), then their sum is 11, giving S the possibilities (2,9), (3,8), (4,7), or (5,6), whose products can all be factored more than one way. Therefore, the numbers must be (3,8).

Quote:

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S. : "Really ?! Then I have know as well !"

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Commentary: S thinks If it were (2,9), whose product is 18, Mr. P could have thought the numbers were (3,6), which would also have fit his statements; since there are two possibilities, how can he know which one? So it can't be (2,9). The same logic holds for (4,7) and (5,6), leaving (3,8) as the only working possibility. Therefore, the numbers must be (3,8).

In conclusion, 3 and 8.

but why not 2 and 9
i thought of the same thing and 2 and 9 look the same to me

okay okay I get it... I forgot the last statement smy mistake

again and again I see that I'm as stupid as it gets...
My I'm a stupid **** :mad: :mad: :mad:

Quote:

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Originally posted by solarflare

In conclusion, 3 and 8.

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Nice idea. But are you sure that no other pair of numbers would fit to the same argumentation?