This greatest common factor game will really help you practice and master this skill.

You have 2 minutes to answer questions

You should use any means necessary to get the answer, such as mental math, paper, and pencils.

However, I strongly recommend that you do not use a calculator!

Here is my guideline to verify how well you are doing:

Easy and 15-25 points in 2 minutes: Very well, keep up!

Easy and 25-35 points in 2 minutes: good!

Easy and more than 35 points in 2 minutes: Expert!

Moderate and 5-15 points in 2 minutes: Very well, keep up!

Moderate and 15-25 points in 2 minutes : Good!

Moderate and more than 25 points in 2 minutes: Expert!

Difficult and 3-10 points in 2 minutes: Very well, keep up!

Difficult and 10-20 points in 2 minutes : Good!

Difficult and more than 20 points in 2 minutes: Expert!