# What is the greatest common factor of 55 and 81?

You have reached us maybe looking for answers to the questions like: What is the greatest common factor of 55 and 81? or what is the highest common factor (HCF) of 55 and 81?

## What is the GCF of 55 and 81?

The first step to find the gcf of 55 and 81 is to list the factors of each number. The factors of 55 are 1, 5, 11 and 55. The factors of 81 are 1, 3, 9, 27 and 81. So, the **Greatest Common Factor** for these numbers is 1 because it divides all them without a remainder. Read more about Common Factors below.

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

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## How to find the Greatest Common Factor

### GCF example:

The first step is to find all divisors of each number. For instance, let us find the gcf(55, 81).

In this case we have:

- The factors of 55 (all the whole numbers that can divide the number without a remainder) are 1, 5, 11 and 55;
- The factors of 81 are 1, 3, 9, 27 and 81.

The second step is to analyze which are the common divisors. It is not difficult to see that the 'Greatest Common Factor' or 'Divisor' for 55 and 81 is 1. The GCF is the largest common positive integer that divides all the numbers (55, 81) 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.

### Greatest Common Factor Calculator

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