What is the Greatest Common Factor of 840 and 845?

Greatest common factor (GCF) of 840 and 845 is 5.

GCF(840,845) = 5

We will now calculate the prime factors of 840 and 845, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 840 and 845.

How to find the GCF of 840 and 845?

We will first find the prime factorization of 840 and 845. After we will calculate the factors of 840 and 845 and find the biggest common factor number .

Step-1: Prime Factorization of 840

Prime factors of 840 are 2, 3, 5, 7. Prime factorization of 840 in exponential form is:

840 = 2³ × 3¹ × 5¹ × 7¹

Step-2: Prime Factorization of 845

Prime factors of 845 are 5, 13. Prime factorization of 845 in exponential form is:

845 = 5¹ × 13²

Step-3: Factors of 840

List of positive integer factors of 840 that divides 840 without a remainder.

1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 105, 120, 140, 168, 210, 280, 420

Step-4: Factors of 845

List of positive integer factors of 845 that divides 840 without a remainder.

1, 5, 13, 65, 169

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 840 and 845. The biggest common factor number is the GCF number.
So the greatest common factor 840 and 845 is 5.

Also check out the Least Common Multiple of 840 and 845