Solutions by » GCF of two numbers

What is the GCF of 9 and 17?

The GCF of 9 and 17 is 1.

Steps to find GCF

  1. Find the prime factorization of 9
    9 = 3 × 3
  2. Find the prime factorization of 17
    17 = 17
  3. To find the GCF, multiply all the prime factors common to both numbers:

    Note that there are no common prime factors.
  4. Therefore, GCF = 1 (since 1 is a factor of every number)

MathStep (Works offline)

Download our mobile app and learn how to find GCF of upto four numbers in your own time:
Android and iPhone/ iPad


Find HCF of:

GCF Calculator

Enter two numbers separate by comma. To find GCF of more than two numbers, click here.

The greatest common factor (GCF) is also known as greatest common divisor (GCD) or highest common factor (HCF).