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Off-Topic Discussion => General Discussion => Topic started by: Locutus of Borg on September 30, 2009, 09:27:26 pm

Title: Math Brain Teaser
Post by: Locutus of Borg on September 30, 2009, 09:27:26 pm

Does anyone know what should go in the circle with the ? in it?

I thought ti would be 15, and that would fit if the right most number was 8 instead of 7. It might be a typo, but if it isn't; can any of you figure it out?

(http://i751.photobucket.com/albums/xx152/TelexFerra/wtfbbq.jpg?t=1254363969)

Title: Re: Math Brain Teaser
Post by: Blue Lion on September 30, 2009, 09:28:35 pm

It's 15

Title: Re: Math Brain Teaser
Post by: Locutus of Borg on September 30, 2009, 09:30:00 pm

Could you explain your thinking? I thought it was 15, but 21 - 13 =/= 7

Title: Re: Math Brain Teaser
Post by: BloodEagle on September 30, 2009, 10:07:08 pm

Where did you find this?

It certainly looks like a typo, as I can't see any other pattern.

::EDIT::

By the way, whoever designed the layout for that image should suffer.

(http://img.photobucket.com/albums/v74/GenoStar/New-2-1.png)

The drastic changes seem to indicate that there isn't an infinite pattern, or if there is, then there isn't enough information available to make it easily recognizable. I'm guessing that either the 21 was supposed to be a 20 or the 7 was supposed to be an 8.

Title: Re: Math Brain Teaser
Post by: Enigmatic Entity on September 30, 2009, 10:46:14 pm

It's 15. Note how there are two lines going to the left of each bottom circle. Minus the bottom line number from the top and you get the number in the vacant circle.

Which implies that the right most number is 8, like others have said.

Title: Re: Math Brain Teaser
Post by: Locutus of Borg on September 30, 2009, 11:36:51 pm

But we're given that the right-most number is 7

So we're all going with typo then?

Title: Re: Math Brain Teaser
Post by: Uchuujinsan on October 01, 2009, 07:33:50 am

The answer is

Spoiler:

12

not 15

Spoiler:

9+9  + 7+2 = 27
2+7  + 4+5 = 18
1+8  + 3+9 = 21
2+1  + 3+6 = 12
1+2  + 2+8 = 13
1+3  + 2+1 = 7

Note that the first numbers are always dividable by 3, and only when it is no longer (the 28) the pattern gets "changed"

[edit]
Added spoiler tags

Title: Re: Math Brain Teaser
Post by: BloodEagle on October 01, 2009, 11:20:56 am

 :wtf:

I hate it when they cheat.  :no:

Title: Re: Math Brain Teaser
Post by: Locutus of Borg on October 01, 2009, 04:12:46 pm

Quote from: Uchuujinsan on October 01, 2009, 07:33:50 am

The answer is

Spoiler:

12

not 15

Spoiler:

9+9  + 7+2 = 27
2+7  + 4+5 = 18
1+8  + 3+9 = 21
2+1  + 3+6 = 12
1+2  + 2+8 = 13
1+3  + 2+1 = 7

Note that the first numbers are always dividable by 3, and only when it is no longer (the 28) the pattern gets "changed"

[edit]
Added spoiler tags

You're awesome