Khan Academy Wiki
Find the greatest common factor of two (or three) integers
Greatest common divisor 256
Description
Exercise Name: Find the greatest common factor of two (or three) integers
Math Missions: 6th grade (U.S.) Math Mission, Pre-algebra Math Mission, Mathematics I Math Mission, Algebra I Math Mission, Mathematics II Math Mission
Types of Problems: 1

The Find the greatest common factor of two (or three) integers exercise appears under the 6th grade (U.S.) Math Mission, Pre-algebra Math Mission, Mathematics I Math Mission, Algebra I Math Mission and Mathematics II Math Mission. This exercise introduces and practices finding the greatest common factor (also called greatest common divisor).

Types of Problems[]

There is one type of problem in this exercise:

  1. Find the greatest common factor: This problem provides a couple numbers and asks the user to find the greatest common factor of two or three numbers.
    Find the greatest common factor of two (or three) integers

    Find the greatest common factor of two numbers.

Find the greatest common factor of two (or three) integers2

Find the greatest common factor of three numbers.

Strategies[]

This exercise is easy to get accuracy badges and speed badges because there is only one type of problem and experience with fractions increases one's ability to find greatest common factors.

  1. For those experienced with fractions, imagine reducing fractions. The number divided by to reduce a fraction into lowest terms is the greatest common factor.

Real-life Applications[]

  1. Hot dogs and buns are an example of GCF and LCM in real life. For example, LCM can be used to solve this problem: "Hot dogs come in packages of 10, while rolls come in either 8 or 12. What's the smallest number of each they have to buy to have the same number of each?"