### Answers − Highest Common Factor or Greatest Common Factor

1. | What is the highest common factor of 8 and 12? |

The factors of 8 are 1, 2, 4 and 8 | |

The factors of 12 are 1, 2, 3, 4, 6 and 12 | |

So the highest common factor is 4 |

2. | What is the highest common factor of 16 and 24? |

The factors of 16 are 1, 2, 4, 8 and 16 | |

The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24 | |

So the highest common factor is 8 |

3. | What is the highest common factor of 28 and 42? |

The factors of 28 are 1, 2, 4, 6, 14 and 28 | |

The factors of 42 are 1, 2, 3, 6, 7, 14, 21 and 42 | |

So the highest common factor is 14 |

4. | What is the highest common factor of 8 and 24? |

The factors of 8 are 1, 2, 4 and 8 | |

The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24 | |

So the highest common factor is 8 |

5. | What is the highest common factor of 15 and 18? |

The factors of 15 are 1, 3, 5 and 15 | |

The factors of 18 are 1, 2, 3, 6, 9 and 18 | |

So the highest common factor is 3 |

6. | What is the highest common factor of 20 and 32? |

The factors of 20 are 1, 2, 4, 5, 10 and 20 | |

The factors of 32 are 1, 2, 4, 8, 16 and 32 | |

So the highest common factor is 4 |

7. | What is the highest common factor of 18 and 30? |

The factors of 18 are 1, 2, 3, 6, 9 and 18 | |

The factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30 | |

So the highest common factor is 6 |

8. | What is the highest common factor of 15, 24 and 30? |

The factors of 15 are 1, 3, 5 and 15 | |

The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24 | |

The factors of 30 are 1, 2, 3, 5, 6, 10, 15 and 30 | |

So the highest common factor is 3 |

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