# Calculate the Greatest Common Factor or GCF of 1225

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The instructions to find the GCF of 1225 are the next:

## 1. Decompose all numbers into prime factors

1225 | 5 |

245 | 5 |

49 | 7 |

7 | 7 |

1 |

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

Prime factors of 1225 | = | 5^{2} . 7^{2} |

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

Common prime factors: 5 , 7

Common prime factors with the lowest exponent: 5^{2}, 7^{2}

## 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** = 5^{2}. 7^{2} = 1225

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