# Calculate the Greatest Common Factor or GCF of 1215

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The instructions to find the GCF of 1215 are the next:

## 1. Decompose all numbers into prime factors

1215 | 3 |

405 | 3 |

135 | 3 |

45 | 3 |

15 | 3 |

5 | 5 |

1 |

## 2. Write all numbers as the product of its prime factors

Prime factors of 1215 | = | 3^{5} . 5 |

## 3. Choose the common prime factors with the lowest exponent

Common prime factors: 3 , 5

Common prime factors with the lowest exponent: 3^{5}, 5^{1}

## 4. Calculate the Greatest Common Factor or GCF

Remember, to find the GCF of several numbers you must multiply the common prime factors with the lowest exponent.

**GCF** = 3^{5}. 5^{1} = 1215

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