Stage: 2, 3 and 4 Challenge Level: 
| 5 | 1 | 3 | 9 | 6 | 2 | 7 | 8 | 4 |
| 4 | 8 | 6 | 7 | 3 | 5 | 1 | 2 | 9 |
| 7 | 2 | 9 | 8 | 1 | 4 | 6 | 3 | 5 |
| 8 | 6 | 5 | 2 | 7 | 9 | 3 | 4 | 1 |
| 1 | 7 | 4 | 6 | 5 | 3 | 2 | 9 | 8 |
| 3 | 9 | 2 | 1 | 4 | 8 | 5 | 6 | 7 |
| 9 | 5 | 8 | 3 | 2 | 7 | 4 | 1 | 6 |
| 2 | 4 | 1 | 5 | 8 | 6 | 9 | 7 | 3 |
| 6 | 3 | 7 | 4 | 9 | 1 | 8 | 5 | 2 |
Logo. Working systematically. Networks/Graph Theory. Counting. Games. Simultaneous equations. Visualising. Mathematical reasoning & proof. Interactivities. Stage 5 - Reviewed 2012.
Published July 2006.
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