Write the digits 1 through 5 in the circles so that each number occurs once in each row and column. The horizontal and vertical equations should be approximately true: both sides will evaluate to positive integers that differ by 1. The first puzzle is solved as an example.

1. | 2. | 3. |

4. | 5. | 6. |

7. | 8. | 9. |

The solutions are here.