| 9 | 5 | 2 | 6 | 3 | 1 | 8 | 4 | 7 |
| 3 | 7 | 8 | 2 | 4 | 5 | 9 | 1 | 6 |
| 1 | 4 | 6 | 9 | 7 | 8 | 5 | 2 | 3 |
| 8 | 1 | 4 | 7 | 5 | 2 | 3 | 6 | 9 |
| 5 | 9 | 7 | 4 | 6 | 3 | 1 | 8 | 2 |
| 6 | 2 | 3 | 1 | 8 | 9 | 4 | 7 | 5 |
| 7 | 6 | 5 | 3 | 1 | 4 | 2 | 9 | 8 |
| 4 | 8 | 9 | 5 | 2 | 6 | 7 | 3 | 1 |
| 2 | 3 | 1 | 8 | 9 | 7 | 6 | 5 | 4 |
Source:
Moore, G. & Stafford, T. (2010). The Rough Guide Book of Brain Training. Rough Guides