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 Dividing A Grid (Posted on 2005-10-25)
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)

 Subject Author Date re(2): my solution Quincy 2005-10-28 12:40:24 re: my solution Quincy 2005-10-28 12:38:22 my solution Aravind 2005-10-26 00:08:54 re: a solution goFish 2005-10-25 21:01:59 re(2): possible subsets of 2? SilverKnight 2005-10-25 15:45:37 a solution SilverKnight 2005-10-25 15:43:51 re: possible subsets of 2? goFish 2005-10-25 15:38:58 re: possible subsets Bob Smith 2005-10-25 12:54:10 possible subsets Charlie 2005-10-25 11:48:45

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