What is the greatest common factor of 91 and 80? - GCD / GCF Calculator

Find the Greatest Common Divisor for any set of integers (2, 3 or more whole mumbers). Here is the answer to the questions like: What is the greatest common factor of 91 and 80? or What is the highest common factor (hcf) of 91 and 80?

To use the GCD / GCF / HCF Calculator below just enter a set of numbers separated by commas (,).

GCD / GCF Calculator

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How to find the Greatest Common Divisor

GCF example:

The first step is to find all divisors of each number. For instance, let us find the gcf(91, 80).

In this case we have:

  • The factors of 91 (all the whole numbers that can divide the number without a remainder) are 1, 7, 13 and 91;
  • The factors of 80 are 1, 2, 4, 5, 8, 10, 16, 20, 40 and 80.

The second step is to analyse which are the common divisors. It is not difficult to see that the 'Greatest Common Factor' or 'Divisor' for 91 and 80 is 1. The GCF is the largest common positive integer that divides all the numbers (91, 80) without a remainder.

The GCF is also known as:

  • Greatest common divisor (gcd)
  • Highest common factor (hcf)
  • Greatest common measure (gcm), or
  • Highest common divisor

To learn more about GCF/GCD, watch this video from Khan Academy or/and read this arcticle.


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