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What is the Greatest Common Factor of 78 and 690?

Greatest common factor (GCF) of 78 and 690 is 6.

GCF(78,690) = 6

We will now calculate the prime factors of 78 and 690, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 78 and 690.

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How to find the GCF of 78 and 690?

We will first find the prime factorization of 78 and 690. After we will calculate the factors of 78 and 690 and find the biggest common factor number .

Step-1: Prime Factorization of 78

Prime factors of 78 are 2, 3, 13. Prime factorization of 78 in exponential form is:

78 = 21 × 31 × 131

Step-2: Prime Factorization of 690

Prime factors of 690 are 2, 3, 5, 23. Prime factorization of 690 in exponential form is:

690 = 21 × 31 × 51 × 231

Step-3: Factors of 78

List of positive integer factors of 78 that divides 78 without a remainder.

1, 2, 3, 6, 13, 26, 39

Step-4: Factors of 690

List of positive integer factors of 690 that divides 78 without a remainder.

1, 2, 3, 5, 6, 10, 15, 23, 30, 46, 69, 115, 138, 230, 345

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 78 and 690. The biggest common factor number is the GCF number.
So the greatest common factor 78 and 690 is 6.

Also check out the Least Common Multiple of 78 and 690