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#1 2006-10-23 06:42:11

jacquimurphy
Member
Registered: 2006-10-23
Posts: 1

number puzzle

my puzzle is this, i have eight houses in a square. nothing in the middle of course. i have  36 people to put into these houses. i can only use each number( 1-8) once and all rows and columns must add up to 15.i can solve the puzzle but iwould like to know if there is a formula that would help if the values were changed. thanks in advance if anyone can help.

regards jacquiup

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#2 2006-10-23 16:44:15

pi man
Member
Registered: 2006-07-06
Posts: 251

Re: number puzzle

I would like to see your solution.    If each column (or each row) must add up to 15 and there are 3 columns, that's 45 people.   And you only have 36.

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#3 2006-10-23 17:01:48

pi man
Member
Registered: 2006-07-06
Posts: 251

Re: number puzzle

Unless you don't count the row and column which goes through the center square?   If that's the case, then there is a solution.   Label the houses as follows:


A     B     C
D            E
F     G     H

The top row (A, B, & C) and the bottom row (F, G & H) add up to 15 each for a total of 30.  That means houses D and E must add up to 6.  Likewise. houses B plus G have 6 people total.   Using each number 1 through 8 once and only once, there are only 2 sets of numbers that add up to 6 ==> 1+5 and 2+4.   That leaves 3, 6, 7 and 8 for the corner squares.  Let's go ahead and put 5 in spot B.   That means A+C = 10 and therefore A and C must be 3 and 7. 

3    5    7
D         E
F     1   H

Now look at the column with the 3.   We know D and E are going to be filled in with 2 and 4.   D can't be the 2 since that would make F=9.   So D=4, E = 2, F = 8 and H = 6.

3   5   7
4        2
8   1   6.

So there's really only 1 solution.   Any other  "solution" is just some rotation or mirror image of the above.

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