Each of the puzzles below is actually 3 puzzles in 1. First black out 2 squares so that the remaining equation is true. Then black out 3 squares to make a correct equation. Then do it with 4 squares. (The standard order of operations is used: multiplication and division are done before addition and subtraction. Only whole numbers are used, though the results might be negative.)

1. | 2. |

3. | 4. |

5. | 6. |

7. | 8. |

9. | 10. |

11. | 12. |

The Solutions are here.