Greatest Common Divisor

These lessons, with videos, examples and step-by-step solutions, explain how to find the greatest common divisor (GCD) or greatest common factor (GCF) using the definition, factor tree, repeated division, ladder method, Euclidean Algorithm.

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Related Pages
Finding Greatest Common Factor
Least Common Multiple - LCM
More Arithmetic Lessons
Free Math Worksheets

The following diagrams show how to find the greatest common divisor (GCD). Scroll down the page for more examples and solutions on finding the greatest common divisor.

Greatest Common Divisor

Greatest Common Divisors (GCDs)
Learn the definition of the “greatest common divisor” and solve three examples.


  1. Find gcd(12, 15)
  2. Find gcd(9, 10)
  3. Find gcd(9, 12, 21)

How to find the Greatest Common Divisor, using the factor tree method?


  1. Find the GCD of 72 and 8.
  2. Find the GCD of 76 and 52.

Use “repeated division”, “double division” or the “ladder method” to find the GCF or GCD of two numbers

Find the GCD of 24 and 60

How to Find the Greatest Common Divisor by Using the Euclidean Algorithm?

Find GCD(10, 45)
Find GCD(1701, 3768)

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