Wednesday, May 26, 2010

Dots and Rows

This is an old one my dad told me, though I've also heard it as a CarTalk puzzler before:




Above is a straight row of 4 dots: it is a 4-dot row.
Next, we have a set of 13 dots that creates 5 different 4-dot rows.

 









Now again create 5 different 4-dot rows, but using only 10 dots.  Rows must be straight.  Oh, and before you tricksters try giving me a single long string of dots, a 5-dot row does not count as 2 4-dot rows.  You can use a dot multiple times, but rows can't overlap.






Solution:
It's a five-pointed star, where every vertex is a dot. 

2 comments:

  1. Nick Guthrie (Dad)June 24, 2010 at 5:33 AM

    I give my students a gold star when they solve this one

    ReplyDelete
  2. Okay, but that uses only five dots...

    ReplyDelete