What is the greatest common factor of 81 and 90?

Answer 1

The GCF of 81 and 90 is: 9

Definition: A factor is a divisor - a number that will evenly divide into another number. The greatest common factor of two or more numbers is the largest factor that the numbers have in common.

Method:

One way to determine the common factors and greatest common factor is to find all the factors of the numbers and compare them.

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

The factors of 90 are 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, and 90.

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

Answer 2

It is not specified what greatest common is to be found out. So we can consider two cases:

1 - The factor

However we basically deal with greatest common factor so the greatest common factor of 81 and 90 is 1.

Visit the related question(below) to see how the GCF of 90 and 81 is obtained.

2 - The multiple

There are infinite common multiples between two numbers so greatest common multiple can't be calculated.