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gavinksong

Member Since 09 Jul 2013
Offline Last Active Dec 17 2014 05:36 PM
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#340729 Retirement

Posted by gavinksong on 23 October 2014 - 12:25 PM

Spoiler for One key to this puzzle is that a person does not necessarily apply for a bus pass the day they reach the retirement age.

This is incorrect because the minimum requirement only advances three months at a time. It does not suddenly jump forward by a year.

Spoiler for

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#340728 Pecular Spectra

Posted by gavinksong on 23 October 2014 - 12:19 PM

Spoiler for answer

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#340726 Pecular Spectra

Posted by gavinksong on 23 October 2014 - 11:13 AM

Oh wait.
Spoiler for

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#340609 Upside Down Cake

Posted by gavinksong on 16 October 2014 - 05:27 PM

(This puzzle is from a blog called By Way Of Contradiction.)

Imagine you have a circular cake, that is frosted on the top. You cut a d degree slice out of it, and then put it back, but rotated so that it is upside down. Now, d degrees of the cake have frosting on the bottom, while 360 minus d degrees have frosting on the top. Rotate the cake d degrees, take the next slice, and put it upside down. Now, assuming the d is less than 180, 2d degrees of the cake will have frosting on the bottom.

If d is 60 degrees, then after you repeat this procedure, flipping a single slice and rotating 6 times, all the frosting will be on the bottom. If you repeat the procedure 12 times, all of the frosting will be back on the top of the cake.

For what values of d does the cake eventually get back to having all the frosting on the top?
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#334139 Creative Paradox

Posted by gavinksong on 13 July 2013 - 12:08 PM

This also reminds me of this (Concave and Convex by MC Escher):

ConvexAndConcave.jpg


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