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100 frih math riddle thread





Aredon
2 makes 2
3 makes 6
4 makes 18

Following the above pattern, what will 5 make?
First to post a reply with the correct answer wins.
One entry allowed per person so try not to guess.

Good luck and try not to think too hard.
I'll post a clue after 10 wrong answers.
Peterssidan
5 makes 54


3*18 = 54 It increase by 3 multiply the last one.
Aredon
Incorrect.
Such a pattern would be ignoring the key word "makes".
Good try.
saratdear
5 makes 38?

5*4+18
doppleganger
yeah 5 makes 38

coz that is the only logical answer that i cld derive, until u have any illogical answers
Aredon
8 more tries left until I give a clue.
doppleganger merely repeated a previous answer so I'll count your post as thread discussion.
caroline
Utterly stupid guess - 5 makes 8.

2+3=5, 2+6=8
imagefree
caroline wrote:
Utterly stupid guess - 5 makes 8.

2+3=5, 2+6=8


well its not a stupid guess (never under esstimate yourself). You may be th winner.
Aredon
7 more tries left until I give a clue.
endless
another stupid guess...

5 makes 54 ( i know it's already guessed but i came on it on an other way..)

2 ~ 2
3 ~ 6 +1 ~ +4
4 ~ 18 +1 ~ + 12
5 ~ 54 +1 ~ + 36

possibly you understand what i mean, the right one gets multiplied by 3 all time
Star Wars Fanatic
Well, I'm not gonna guess, I don't want to waste my one guess, but this one is a head wringer, I've been puzzling over it for a while now, and can't make any headway.

Good luck to all.
Aredon
Hehe, ok I'll tell you guys what:
I'll reinstate your "one guess" after the first clue is given.
mtorregiani
5 makes 72

70 = 5 * 18 - 18

I'm pretty sure this is the right answer. If it's correct, I'll explain why.
Aredon
6 more tries left until I give a clue.
ninjakannon
I'm another one who thinks it's 54. It appears to be a geometric sequence.

I looked to find a common ratio between the terms, this is of course 3 - as others spotted. You find the common ration by putting 2 consecutive terms of the sequence into a fraction, but the reciprocal of the consecutive order; so, the terms are 2, 6, 18. Putting 18/6 or 6/2 both give 3. Thus, the common ratio is 3. Let the common ratio be r.
Now we have that we must work out a few more terms.

Firstly, here's the formula I'm using: ak = ar^(k-1)
k = the general term (so when the answer is 6, k = 3).
a = the first term of the sequence.
r = the common ratio, as previously (and poorly) explained.
ak = the general term (so a7 is term 7).

That leaves a problem, we don't have a.
However, to find it we simply need to divide the term when k = 2 by the common ratio, which gives 2/3. So a = 2/3.

Now we have all our terms, so:

a5 = (2/3) x 3^4
= 54

Please say I'm right. Razz
gh0strec0n_legit
Aredon wrote:

2 makes 2
3 makes 6
4 makes 18


5 makes 45?

EDIT: Changed answer...5 Makes 90...

2makes2
3(2) = 6
4(6) = 18
5(18*) = 90
Aredon
ninjakannon merely repeated a previous answer so I'll count your post as thread discussion.
gh0strec0n_legit answers 90. Incorrect. Good try.
5 more tries left until I give a clue.
ninjakannon
Aredon wrote:
ninjakannon merely repeated a previous answer so I'll count your post as thread discussion.
gh0strec0n_legit answers 90. Incorrect. Good try.
5 more tries left until I give a clue.

What's irritating is that everyone has their own way of working this out and in their own ways they are correct. It's just not the answer you're looking for. I, for example, approached this question as you would an AS level exam question. If it had been in an AS level exam I would have got the correct answer. Cool
gh0strec0n_legit
How many times can we guess?
Aredon
One entry allowed per person. After I give a clue, you all get your one entry reinstated.
If someone didn't use up their one guess, they don't gain an extra guess since there is nothing to reinstate.
Peterssidan
The problem is that it has more than one answer. I can't guess Silenced so you others, use your brains and solve this. I have nu qlue myself.
mtorregiani
You should really give out a clue.
ninjakannon
mtorregiani wrote:
You should really give out a clue.

Agreed, people aren't guessing any more for a reason. Wink
Aredon
mtorregiani wrote:
You should really give out a clue.

Yeah, I've been itching to give it out but I was being held back by my words:
Aredon wrote:

I'll post a clue after 10 wrong answers.

Might as well give it then, I thought the 10 guesses would have been used up by now.

Here's the clue:
8+8=10
Hehe, well 8+8=16 however the above is a big clue.
Also:
The word "makes" is a key to the pattern I'm looking for.
Example: 2 decks make 104 cards hence 2 makes 104.
However the above pattern requires the example to concern cards.
The pattern I'm looking for doesn't have to involve any specific person, place or thing but rather concerns all movable matter within the 3 spatial dimensions.

Everyone's "one guess" is reinstated since the clue has been given.

Here's the pattern from my first post again so you don't have to scroll up:
Aredon wrote:

2 makes 2
3 makes 6
4 makes 18
Peterssidan
Then I know...
5 makes 78

The numbers here is in hex.

2! = 2
3! = 6
4! = 18(hex) = 24(dec)
5! = 78(hex)

therefore the answer is 78! Very Happy
endless
Peterssidan wrote:
Then I know...
5 makes 78

The numbers here is in hex.

2! = 2
3! = 6
4! = 18(hex) = 24(dec)
5! = 78(hex)

therefore the answer is 78! Very Happy


that one is the winner, i know it for sure... Very Happy
ninjakannon
endless wrote:
that one is the winner, i know it for sure... Very Happy

It definitely sounds right. But so did the suggestions before this clue! However, Peterssidan has used factorials so it seems to be more in conjunction with the "makes" that's used in the question.

Awaits answer with bated breath. Razz
Aredon
Peterssidan wrote:
Then I know...
5 makes 78

The numbers here is in hex.

2! = 2
3! = 6
4! = 18(hex) = 24(dec)
5! = 78(hex)

therefore the answer is 78! Very Happy

Correct! 5! to hex is 0x78 hence 5 makes 78.
All the numbers were in hexadecimal, decimal is usually taken for granted since we are so used to using the decimal system.
The logic behind it all is that 2 letters can be arranged either ab or ba hence they can be arranged in 2 ways. In other words 2 letters can be arranged in 2 possible combinations hence 2 makes 2.
Of coarse we don't need to be talking about letters, it could have been cards in a deck or beads on a string...
3 letters can be arranged abc acb bac bca cab cba hence 6 combinations.
4 letters can be arranged 24 ways (or 0x18 in this case).
5 letters can be arranged 120 ways (or 0x78 in this case).


The 100 frih$ have been donated to Peterssidan. Congratulations!
Peterssidan
Thank you! Smile
It was not very hard after you said that 8+8=10.
ninjakannon
Aredon wrote:
3 letters can be arranged abc acb bac bca cab cba hence 6 combinations.

You mean permutations. Wink

I've only receintly gone over Combinations and Permutations as well as factorials so I'm a bit miffed that I didn't work this out. I knew 8+8=10 was a big clue but couldn't get it!

So well done Peterssidan!
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