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You were given 12 coins by your friend. He bet that if you could arrange these dozen coins into 6 rows of 4 coins such that it makes two similar shapes, he will give you 12 more coins. How will you do it?

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  • $\begingroup$ Both Jonthemon's answer and Deusovi's seem correct. $\endgroup$ – Spacemonkey Aug 17 '15 at 16:38
  • $\begingroup$ Do the shapes have to be enclosed? $\endgroup$ – Eric Aug 17 '15 at 18:15
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Forgive the badly drawn image:

enter image description here

Black are the coins, green are the rows of 4, red is the similar shape.

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  • $\begingroup$ @jonthemon The image looks like the answer to me, and after some looking I can see the 6 rows. But I suggest you modify it to highlight the six lines of 4 coins, instead of the two hexagons. $\endgroup$ – AJFaraday Aug 17 '15 at 15:22
  • $\begingroup$ Isn't that only 5 rows? $\endgroup$ – Kingrames Aug 18 '15 at 11:50
  • $\begingroup$ no, 6 green lines for the 6 rows. You can easily see it without the lines by only counting one row per corner of the hex, ending every other corner. 6 corners = 6 lines. $\endgroup$ – Spacemonkey Aug 18 '15 at 19:10
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You arrange them into...

a star of David, with each point and intersection having a coin.

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o  o
oooo
oooo
o  o

Based on @AlexHurst answer.

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  • $\begingroup$ Where are the similar shapes? $\endgroup$ – Deusovi Aug 18 '15 at 12:03
  • $\begingroup$ @Deusovi that arrangement is reflective vertically and horizontally, so there are two different pairs of similar shapes. (a narrow 'D' and its reflection, or a squared 'U' and its reflection) $\endgroup$ – dfperry Aug 18 '15 at 12:06
  • $\begingroup$ Or simply a smaller square inside a bigger square $\endgroup$ – Spacemonkey Aug 18 '15 at 19:12

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