GCF of 2 Numbers, Trick Finds it Fast

Ever need to find the GCF of two numbers? Here’s a trick for finding the GCF of any two numbers — very quickly. This is an original trick, so I doubt you’ll find it anywhere else online. But most important, it’s easy to use, and it works no matter how large the numbers might be. Also nice … learning this […]

The GCF (aka GCF) … what is it?

The GCF is the greatest common factor, and it’s a key concept in math. This term is also known as the GCD, the greatest common divisor. Students often need to find this quantity either for a pair of numbers or for three or more numbers. For example, knowing the greatest common factor allows students to reduce […]

Find the LCM in a way that makes sense! (Part 2)

Two little exceptions to the technique laid out in yesterday’s post. To make sure you don’t overlook the exceptions, read this post today.

Find the LCM in a way that makes sense! (Part 1)

For the most part, when you set out to find the least common multiple for a pair of numbers, you are asked to go through a bunch of steps that don’t really make sense. Till now! Here’s a way to find the LCM that truly does make sense. This post explains it in clear English, […]

How to factor out the GCF with stories

Real-life stories, related to algebraic procedures, can dramatically help students understanding both what the process is about, and how to do the process. Here I show how two real-life stories can help students master the steps required for factoring the GCF out of a polynomial.

Recent insight on the GCF (and GPGCF)

Two factors limit the size of the GCF for any two numbers. Those factors are: 1) the difference between the two numbers, and 2) the size of the smaller of the two numbers. Whichever of these two factors is smaller is the Greatest Possible Greatest Common Factor, also known as the GPGCF.