# keep-flip-change

Let $a,b,c,d\in \mathbb{Z}-\{0\}$. A mnemonic device for calculating

$$\frac{a}{b}\xf7\frac{c}{d}$$ |

is KFC. This stands for ”keep-flip-change”. This means that you keep the first fraction as it is, flip the second fraction, and change the problem to a multiplication problem. Thus, the expression above becomes

$$\frac{a}{b}\cdot \frac{d}{c}.$$ |

This yields that

$$\frac{a}{b}\xf7\frac{c}{d}=\frac{a}{b}\cdot \frac{d}{c}=\frac{ad}{bc}.$$ |

Title | keep-flip-change |
---|---|

Canonical name | Keepflipchange |

Date of creation | 2013-03-22 15:59:52 |

Last modified on | 2013-03-22 15:59:52 |

Owner | Wkbj79 (1863) |

Last modified by | Wkbj79 (1863) |

Numerical id | 4 |

Author | Wkbj79 (1863) |

Entry type | Definition |

Classification | msc 97D40 |

Synonym | KFC |

Synonym | K.F.C. |