Learning the rules of divisibility helps all students succeed at math. Learning the trick for 6 is really helpful because it is not easy to see if 6 goes in for most people. This trick makes it much easier to tell.

# Archive | Number Theory

# Divisibility: Find out if 3 divides evenly into an integer

Learning the divisibility tricks speeds up mental math. How to know if 3 divides into a number evenly? This blog tells you how

# From GPGCF to GCF … in two easy steps

For any pair of numbers, how to find the GCF once you know the GPGCF.

# 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.