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10 replies to this topic

#1 flamebirde

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Posted 24 October 2012 - 04:10 AM

Saw this one on a test. Think outside the box.

9*2=13
5*3=11
4*9=21
9*4=17

What does 7*8 equal?
note: the * does not indicate multiplication. It indicates some sort of action or actions.
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#2 ohiocpa1

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Posted 24 October 2012 - 04:32 AM

double the smaller number, add to the larger
7*8 = (2x7) + 8 = 22
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#3 Caliban27

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Posted 24 October 2012 - 08:12 AM

double the smaller number, add to the larger
7*8 = (2x7) + 8 = 22

That won't work, 'cause 4*9 would be 17 not 21.
A variation to that theme which would work is: if second number is smaller, then [first number] + twice [second number], else, [first number] + twice second number] - 1. That is quite inelegant, and does not solve for instance of both numbers the same. Back to thinking further outside cube.

Edited by Caliban27, 24 October 2012 - 08:12 AM.

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#4 Emil

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Posted 24 October 2012 - 09:22 AM

Spoiler for Am I on the right track?

Edited by Emil, 24 October 2012 - 09:23 AM.

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#5 CaptainEd

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Posted 24 October 2012 - 03:30 PM

Spoiler for Not much more elegant, but fits the data we have

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#6 vinay.singh84

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Posted 24 October 2012 - 05:17 PM

Spoiler for Not much more elegant, but fits the data we have


floor(x + 1) is more easily written as ceil(x)
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#7 Pickett

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Posted 24 October 2012 - 05:41 PM

floor(x + 1) is more easily written as ceil(x)

He's not flooring x+1...he's flooring (x+1) / 2...just FYI...
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#8 CaptainEd

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Posted 24 October 2012 - 05:48 PM

Spoiler for Thanks to Vinay and Pickett, slightly more compact...

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#9 flamebirde

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Posted 25 October 2012 - 12:28 AM

oops, sorry... screwed up on 4*9. it should equal 22.
REVISED QUESTION:

9*2=13
5*3=11
4*9=22
9*4=17

What does 7*8 equal?
note: the * does not indicate multiplication. It indicates some sort of action or actions.

With this in mind, Emil is very close to the answer but not quite.
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#10 Rob_Gandy

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Posted 25 October 2012 - 01:03 AM

Spoiler for Hm..

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