Four fours is a maths puzzle to find the simplest mathematical expression for every integer from 0 onwards. The rules are simple;

- You can only use the operators; +, -, x, (brackets) , x² square and ! factorial
- You can only use the number four
- Each expression must have four fours

Anyway, having some spare time I decided to have an attempt at 0 - 20;

Number | Answer |
---|---|

0 | (4 + 4) - (4 + 4) |

1 | (4 + 4) / (4 + 4) |

2 | (4 / 4) + (4 / 4) |

3 | ( (4 + 4) + 4) / 4 |

4 | ( (4 - 4) * 4) + 4 |

5 | ( (4 * 4) + 4) / 4 |

6 | ( (4 + 4) / 4) + 4 |

7 | (4 + 4) - (4 / 4) |

8 | (4 - 4) + (4 + 4) |

9 | (4 / 4) + (4 + 4) |

10 | 44 / 4.4 |

11 | (4 / .4) + (4 / 4) |

12 | 4 x (4 - (4 / 4)) |

13 | (4!) - (44 / 4) |

14 | 4 + 4 + 4 + ?4 |

15 | (44 / 4) + 4 |

16 | (4 + 4) + (4 + 4) |

17 | (4 / 4) + (4 x 4) |

18 | (4 x 4) + 4 - ?4 |

19 | 4! - 4 - (4 / 4) |

20 | 4 x (4 / 4 + 4) |

I'm sure there are many different ways you can achieve each integer, but these are the simplest ones I could think of at the time.