We all know about magic squares. Aren't they special , huh ?
Draw a square with same numbers of row as column. Do you know if certain values are added in it then the sum of values of each row , each column and each of the two diagnols is the same. Condition , that natural numbers till the total number of cells in the square can be entered . For example , there is a square with rows and columns 5 then positive values upto 25 , the total number of cells , can be entered with , one more condition that any number once entered in the square COULD NOT be entered in the square AGAIN . NO block should be left empty. One more information , the two diagonals are from top leftmost cell to bottom rightmost cell and top rightmost cell to bottom leftmost cell.
An example of magic square,
8 | 3 | 4 |
1 | 5 | 9 |
6 | 7 | 2 |
NOTE : The image of this square might appear irregular but it's a square with 9 cells, and please do try to understand it. Where you shall see sum of every row , column and each of two diagnols is 15.
Now , for the problem , if there exist , as will surely exist , a magic square with number of row and column 11 or with total number of cells 121 , what will be the sum of each row , column or diagnal , if it retains all the qualities of a magic square ?
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let n= no. of rows let s= sum of all in 1 row normally, the sum is the middle number of no. of sq * n so, first, no. of sq = n 2 the mid number = 2 n 2 − 1 so, s = n ∗ 2 n 2 − 1
It will surely be there in case of magic square with odd rows and columns , that there exists a centre cell , I think you could try to visualize it , which is exactly at the centre of the square. Now consider the row and column and diagnal which pass through the centre cell . We know their sum should be same . But how , let's apply some strategy or tricks by which it could be same . I have found one which we shall discuss . Let there be a number m in the centre cell , then we could write a number _ m-p _ on top of it and m+p below it and m-q on top of m-p and m+q below m+p and so on on both row and column with defferent values in place of p or q but the sum would be same as the values would get cancel. So what we will get constant value of two diagnal , a column and a row . And in this way we will by logic enter rest of the values . The value of the centre cell should be middle of the values that can be entered , so in a cell which has n rows and columns with values that can be entered be n 2 , then we have a formula for finding the middle number median that has to be entered in the centre cell , 2 n 2 + 1 And so we can easily get the sum of each row , column and each of the two diagnols as , by a little , that as the sum of each column , row and diagnal could be found by just finding that of anyone , so we try for the column of centre cell . Which is got by adding , m , m-p , m+p , m-q , m+q ...... , and all p's or q's would get cancelled so this gives us the sum to be n × m and m being equal to 2 n 2 + 1 we have the formula for sum for each row , column or diagnal as n 2 n 2 + 1 Substituting n for 1 1 we have answer 6 7 1
http://en.wikipedia.org/wiki/Magic_square
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True , eh.... I never thought the same would be there too , for this idea came in my mindlong ago and was planning to post it on brilliant.
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There are total 121 small squares and numbers are form 1 to 121 sum of these 121 numbers = 121 × 122/2 = 7381
This sum 7381 is divided in 11 columns , rows and diagonals so magic sum = 7381/11 = 671 the following arrangement is shown for 11 × 11
68 81 94 107 120 1 14 27 40 53 66
80 93 106 119 11 13 26 39 52 65 67
92 105 118 10 12 25 38 51 64 77 79
104 117 9 22 24 37 50 63 76 78 91
116 8 21 23 36 49 62 75 88 90 103
7 20 33 35 48 61 74 87 89 102 115
19 32 34 47 60 73 86 99 101 114 6
31 44 46 59 72 85 98 100 113 5 18
43 45 58 71 84 97 110 112 4 17 30
55 57 70 83 96 109 111 3 16 29 42
56 69 82 95 108 121 2 15 28 41 54
Using this technique any odd number magic square can be arranged.