How to Find the GCF of a Composite Number

By Stefan Robert

The acronym GCF stands for greatest common factor. Find the GCF of a composite number with help from an expert in computers, with two degrees in both Computer Science and Applied Mathematics, in this free video clip.


Hi, my name's Stefan. Today, I'm gonna be speaking on how to find the GCF or greatest common factor of a composite number. Let's take the numbers 35 and 28. What I'm gonna do is I'm gonna use the method of subtraction. You subtract the smaller number from the bigger number and keep going till they're equal. So I'm gonna take 35 and put this notation over 28, then I'm gonna take the smaller number 28 subtract it from the larger, in this case I get 7. Then I take the smaller number again subtract it from the larger 21 then take the smaller number again subtract from the larger then I get 14. I'm gonna keep going, take the smaller number subtract from the larger and I get 7 and just stop when their equal so 7 is the greatest common factor.