Ok! this one stumps me.

rondon · #1 10-21-2005, 06:01 AM

http://trunks.secondfoundation.org/files/psychic.swf

Caitlin · #2 10-21-2005, 06:57 AM

Do you really want the answer?

Spoiler space..

Highlight to reveal:
Every combination results in the same symbol. The symbol is changed every round, but it is the same for any number you pick. Clever though!

Panpan · #3 10-21-2005, 07:29 AM

Caitlin beat me to it!

Every legal answer for double-digit numbers results in a multiple of 9. The Excel formula is =a1-(int(a1/10)+mod(a1,10)) where a1 is the number you chose. This simplifies to =9*int(a1/10). For example, 12 gives a result of 9; 22 gives 18; 32 gives 27; etc.

All those multiples have the same symbol on the web page. (The symbol for 0 is also the same although 0 is not a possible result). The symbols change randomly for each attempt to make things more mysterious.

Pierre

rondon · #4 10-21-2005, 08:35 AM

ok I see... back to the riddles of my era:

so if an egg and a half cost a cent and a half what does a dozen cost?

Marthig · #5 10-21-2005, 03:54 PM

12 ?

rondon · #6 10-21-2005, 04:05 PM

..................

Marthig · #7 10-21-2005, 04:17 PM

Quote:

Originally Posted by rondon

..................

hehe

I did it !

have just remembered one

:

how much is the half of two plus two

Caitlin · #8 10-21-2005, 05:54 PM

3? (Depending on where the brackets are...)

rondon · #9 10-21-2005, 05:57 PM

....................

kschulz · #10 10-21-2005, 09:14 PM

2 and 3 are both correct - depending on where the brackets are, like Caitlin said.

Marthig · #11 10-22-2005, 08:18 AM

Quote:

Originally Posted by kschulz

2 and 3 are both correct - depending on where the brackets are, like Caitlin said.

The riddle, puzzle or whatever the name is, is from those typical school (pre- algebra times) things.
Mainly a word game I would say. The brackets would make it lose the fun

The answer as I was taught is 3 -and the "formula" would be: the half of 2+(2)

P.S.: I am from Rondon's times, even older I think

Caitlin · #12 10-22-2005, 08:23 AM

Can someone explain the egg and a half one to me? I don't quite 'get' what the riddle is supposed to be?

kschulz · #13 10-22-2005, 09:35 AM

Caitlin,

I think the point of the riddle is realizing that solving it shouldn't be as difficult as one might think (some might do a lot more math than needed because the "fractional" aspect makes them think they need to). Once you realize that an egg costs a cent, its easy to see what a dozen costs without much thought.

- Kurt

rondon · #14 10-22-2005, 10:46 AM

Another that I used to enjoy more was nearly as simple,

On the way back from a fishing trip one man said to the other... give me one of your fish and we will be even... the other said well give me one of yours and I will have twice as many ... how many did each man have?

Panpan · #15 10-22-2005, 10:54 AM

Quote:

Originally Posted by kschulz

2 and 3 are both correct - depending on where the brackets are, like Caitlin said.

If the answer were 3, there was the opportunity to put a comma in the sentence to avoid ambiguity: "How much is the half of two, plus two?" Since there is none, the better answer is 2.

Pierre

MaryLynn · #16 10-22-2005, 11:27 AM

Quote:

Originally Posted by rondon

the other said well give me one of yours and I will have twice as many ...

Twice as many as what? Will the second man have twice as many as the first man presently has or twice as many as the first man after the transfer? Or am I making this too difficult?

MaryLynn

Panpan · #17 10-22-2005, 12:41 PM

Quote:

Originally Posted by rondon

On the way back from a fishing trip one man said to the other... give me one of your fish and we will be even... the other said well give me one of yours and I will have twice as many ... how many did each man have?

The answer is 5 and 7.

Pierre

NancyJ · #18 10-23-2005, 02:12 AM

without any brackets the answer is 3.
Its a basic rule of mathmatics... division and mutiplication come before addition.
Since a half can either mean mutliply by a half or divide by 2, that part comes first.
http://www.easymaths.com/What_on_earth_is_Bodmas.htm

Panpan · #19 10-23-2005, 03:21 AM

Quote:

Originally Posted by NancyJ

without any brackets the answer is 3.
Its a basic rule of mathmatics... division and mutiplication come before addition.
Since a half can either mean mutliply by a half or divide by 2, that part comes first.
http://www.easymaths.com/What_on_earth_is_Bodmas.htm

Easymaths.com overstates the case. Operator precedence is merely a matter of convention. Although "bodmas" is common, there are other conventions with merit. For instance, Hewlet Packard still uses RPN in their high-end calculators. Consider also the case of computer languages like APL with a large number of operators; precedence levels for specific operators would be unwieldly so only left to right or right to left precedence is kept. There are other conventions in use.

So I maintain my answer. The questioner could have avoided ambiguity if the answer were 3.

Pierre

kschulz · #20 10-23-2005, 07:40 AM

Pierre, technically you make good points. Yes, there may be other conventions that could be considered. However, I have to agree with NancyJ on this one - without brackets (or commas, or any other information), the correct answer is 3 given the generally accepted rules of precedence.

Sure, a comma might have removed the ambiguity, but it would not make a very good riddle then, would it?

- Kurt