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Setting the Table

Fill the grid with consecutive numbers.

The sums of the rows and columns are shown.

ID:
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Here is a 3 x 3 table. The row sums are show at the right, the column sums at the bottom.

7
18
13
14
13
21
11

We have the numbers 1 2 3 4 5 6 7 8 9 to work with. 21 – 7 = _ + _. So we need two numbers that sum to 14; candidates are: 5 + 9 and 6 + 8. We’ll just guess and hope for the best.

7
6
8
18
13
14
13
21
11

Since 13 is the smallest row, we’ll try that next: 13 = 6 + _ + _. Candidates are: 2 + 5, 3 – 4. Guess again:

7
4
6
3
8
18
13
14
13
21
11

The only possibility for row 3 is: 14 = 8 – 1 + 5, but this won’t work: if you put 5 in column 3 then: 11 = 5 + 3 + 3 and if you put 1 in column 3 you get: 11 = 1 + 3 + 7. Let’s swap the 3 and 4 in row two and see what happens:

7
3
6
4
8
18
13
14
13
21
11

Now we try column three: 11 = 5 + 4 + 2, which works and then column one: 13 = 1 + 3 + 9, which also works.

9
7
2
3
6
4
1
8
5
18
13
14
13
21
11

Fortunately, the row one sum works out and the puzzle is solved. Our choice and placing of 6 and 8 at the start was lucky indeed! Is there a better strategy .. try to find one.

Have fun!