How to find the Greatest Common Factor?

The GCF (Greatest Common Factor) of two or more numbers is the greatest number among all the common factors of the given numbers.

How to find GCF fast?
Step 1 - List out the factors of each number.
Step 2 - Mark all the common factors.
Step 3 - GCF is the product of the factors that are common to each of the given numbers.

[Straykidssecondfather]

I’m not sure how to list out the factors though

[haianglenguyen]

Ngoài sơ cây đồ ta còn có thể tính bội chung nhỏ nhất bằng cách của Eclid là phân tích ra thừa số nguyên tố

[SuzanneEaton-wj]

What if there is only one number that is the same

[AllysonSandoval-sqnw]

To those who dont know why she only circled specific numbers: You only circle the prime numbers