What is the greatest common factor of 20 55 and 85?

The GCF of 20, 55, and 85 is 5

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

The factors of 20 are 1, 2, 4, 5, 10, and 20.

The factors of 55 are 1, 5, 11, and 55.

The factors of 85 are 1, 5, 17, and 85.

The common factors are 1 and 5. Therefore, the greatest common factor is 5.

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

The prime factors of 20 are 2, 2, and 5.

The prime factors of 55 are 5 and 11.

The prime factors of 85 are 5 and 17.

The prime factors in common are a single 5, so the greatest common factor is 5.