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What number should replace the question mark?

Tis is driving me crazy. I can't see no pattern.

389----21----492

|.....\......./.....|

|......\...../......|

|.......\.../.......|

16........?........10

|......./...\.......|

|....../.....\......|

|...../.......\.....|

613----5----841

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On 21/5/2005 at 7:40 AM, Guest roger_kang said:

What number should replace the question mark?

Tis is driving me crazy. I can't see no pattern.

389----21----492

|.....\......./.....|

|......\...../......|

|.......\.../.......|

16........?........10

|......./...\.......|

|....../.....\......|

|...../.......\.....|

613----5----841

In each row middle number is sum of all the odd numbers in the circles either side.

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13, not 2-- the sums of odd numbers are along the lines, so the center number should be the sums of the diagonally opposite odd numbers.  In both diagonal directions the odd numbers are 9, 3 and 1 which add to 13.  That is the odd numbers in 613 add to the odds in 492, and the odds in 389 add to the odds in 841.

Edited by OldChemE
fixed a typo

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3 hours ago, OldChemE said:

In both diagonal directions the odd numbers are 9, 3 and 1 which add to 13.

Good point! But could the answer also be 26?
Extract all odd numbers from circles connected via diagonal lines: (389)-->(3+9), (492)-->(9), (841)-->(1), (613)-->(1+3)
Sum: (3+9)+(9)+(1)+(1+3)=26
Why not use all odd numbers from both diagonals?

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Yes Ghideon-- I didn't think of that.

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