Prime Factorization Method
There are multiple ways to find the greatest common factor of given integers. One of these involves computing the prime factorizations of each integer, determining which factors they have in common, and multiplying these factors to find the GCD.
- Find the prime factorization of each number:
315 = 3, 3, 5, 7
90 = 2, 3, 3, 5
- Identify the common prime factors between 315 and 90: 3, 3, 5
- To find GCF multiply the common prime factors: GCF(315, 90) = 45
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Listing All Common Factors Method
To find the Greatest Common Factor (GCF) of 315 and 90 by listing all common factors, follow these steps:
- List all factors of each number:
- Factors of 315: 1, 3, 5, 7, 9, 15, 21, 35, 45, 63, 105, 315
- Factors of 90: 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90
- Identify the common factors of 315 and 90: 1, 3, 5, 9, 15, 45
- Determine the greatest common factor:
- The greatest common factor is the largest number in the list of common factors, i.e. 45
So, the Greatest Common Factor (GCF) of 315 and 90 is 45.