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 Prime Perimeter (Posted on 2005-03-11)

You and two other people have numbers written on your foreheads. You are all told that the three numbers are primes and that they form the sides of a triangle with a prime perimeter. You see 5 and 7 on the other two heads and both of the other people agree that they cannot deduce the number on their own foreheads.

 See The Solution Submitted by Erik O. Rating: 2.8235 (17 votes)

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 re(2): 5,5,9--7,7,9--7,7,13 | Comment 51 of 89 |
(In reply to re: 5,5,9--7,7,9--7,7,13 by pcbouhid)

Sorry. I always initially think of nine as prime and have to kick myself and think no it's not.  It is probably because I am listing 1,3,5,7 and of course I next think 9.  But in another post I just read, Charlie? says that 1 is not considered prime.  I am sure he is right.  So now I have some more rethinking to do about prime numbers.  And of course 7,7,13 adds up to 27 = 3^3, OOH higher level math.  I figured I was worong but I always hate when I am.  I have been out of school way too long.

 Posted by john on 2005-03-14 17:42:51

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