The greatest common factor is the largest factor found in two or more numbers.
The quickest way to find the GCF is to use the Magic Box.
1. Place the numbers you need to compare inside the box
2. Find what you can divide the numbers by
3. Place that factor on the left
4. Divide the numbers and write their quotients under
5. When you can only divide by one you have reached the end.
5. Multiply all of the numbers that you wrote to the left