###### Asked in Factoring and Multiples

# What is the greatest common factor of 63 and 81?

## Answer

###### Wiki User

###### September 19, 2017 3:09AM

## Answer: 9

One way to determine the greatest common factor is to find all the factors of the numbers and compare them. Following will be a quality mathematics help regarding factors:The factors of 63 are 1, 3, 7, 9, 21, and 63.

The factors of 81 are 1, 3, 9, 27, and 81.

The common factors are 1, 3, and 9. Therefore, the greatest common factor is 9.

The greatest common factor can also be calculated by identifying the common prime factors and multiplying them together.

The prime factors of 63 are 3, 3, and 7.

The prime factors of 81 are 3, 3, 3, and 3.

The prime factors in common are 3 and 3, so the greatest common factor is 9.

Comparing the prime factors using exponents:

63 = **3^2** x 7

81 = 3^4 = **3^2** x 3^2

Then GCF is 3^2 = 9

The GCF is 9.

The GCF is 9.

The GCF of 63 and 81 is 9

the GCF of 63 and 81 is 9

The Greatest Common Factor (GCF) is: 9

###### Wiki User

###### September 15, 2017 12:54PM

GCF(63, 81) = 9.