| 1. |
Use the diagonals method.
 | | 15 | -9 | 8 | | 11 | -16 | 3 | | -10 | -1 | -12 |
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| 2. |
Use the diagonals method.
 | | -12 | -20 | -11 | | -6 | 1 | 10 | | 4 | 15 | 12 |
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| 3. |
Use the diagonals method.
 | | 14 | 13 | -18 | | 10 | 0 | -8 | | 4 | 18 | 12 |
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| 4. |
Use the diagonals method.
 | | 13 | 16 | 19 | | -16 | -2 | 20 | | -10 | -18 | 5 |
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| 5. |
Use the diagonals method.
 | | -13 | 9 | -20 | | -10 | -6 | 4 | | -4 | -7 | 1 |
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| 6. |
Use the diagonals method.
 | | 20 | -7 | 18 | | -16 | -5 | 5 | | -11 | 10 | -20 |
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| 7. |
Use the diagonals method.
 | | -13 | -20 | 19 | | -18 | 15 | 8 | | -16 | 2 | 6 |
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| 8. |
Use the diagonals method.
 | | -9 | -1 | 0 | | -3 | 16 | 3 | | -14 | -15 | 17 |
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| 9. |
Use the diagonals method.
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| 10. |
Use the diagonals method.
 | | -10 | 3 | -2 | | 15 | -9 | -11 | | -20 | 16 | 19 |
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| 11. |
Use the diagonals method.
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| 12. |
Use the diagonals method.
 | | 5 | -12 | -18 | | -10 | -1 | -15 | | 7 | 9 | 16 |
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| 13. |
Use the diagonals method.
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| 14. |
Use the diagonals method.
 | | 2 | -14 | 10 | | -18 | 14 | -5 | | -1 | 5 | -9 |
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| 15. |
Use the diagonals method.
 | | -1 | 4 | -15 | | -16 | 6 | 2 | | -18 | -8 | 0 |
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| 16. |
Use the diagonals method.
 | | 12 | 16 | 19 | | -1 | 14 | -8 | | -11 | -18 | -13 |
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| 17. |
Use the diagonals method.
 | | -20 | 0 | 16 | | 17 | -2 | -18 | | -12 | 13 | -11 |
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| 18. |
Use the diagonals method.
 | | -12 | 12 | -16 | | 0 | -11 | 7 | | 8 | -20 | 1 |
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| 19. |
Use the diagonals method.
 | | -16 | 4 | -15 | | 13 | 3 | -5 | | 14 | 8 | -8 |
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| 20. |
Use the diagonals method.
 | | -12 | 3 | -14 | | 11 | -10 | 15 | | 17 | 16 | 13 |
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| 21. |
Use the diagonals method.
 | | -10 | -12 | -9 | | 18 | 20 | -18 | | 7 | -17 | 16 |
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