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Dividing A Grid (Posted on 2005-10-25) Difficulty: 3 of 5
Each square of the 5x5 grid below contains a number 1-25. Divide the grid into five regions so that the number of squares and the sum of the squares in each region are both odd prime numbers. (1 is not a prime)
For example, the region consisting of {2,3,8} is a valid region. It contains 3 squares (3 is an odd prime) and the sum of the numbers in the squares is prime (2+3+8=13 is an odd prime).
+--+--+--+--+--+
| 1| 2| 3| 4| 5|
+--+--+--+--+--+
| 6| 7| 8| 9|10|
+--+--+--+--+--+
|11|12|13|14|15|
+--+--+--+--+--+
|16|17|18|19|20|
+--+--+--+--+--+
|21|22|23|24|25|
+--+--+--+--+--+

See The Solution Submitted by Brian Smith    
Rating: 2.0000 (1 votes)

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re(2): my solutionQuincy2005-10-28 12:40:24
re: my solutionQuincy2005-10-28 12:38:22
Solutionmy solutionAravind2005-10-26 00:08:54
re: a solutiongoFish2005-10-25 21:01:59
re(2): possible subsets of 2?SilverKnight2005-10-25 15:45:37
a solutionSilverKnight2005-10-25 15:43:51
re: possible subsets of 2?goFish2005-10-25 15:38:58
re: possible subsetsBob Smith2005-10-25 12:54:10
Hints/Tipspossible subsetsCharlie2005-10-25 11:48:45
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