If you want someone to stop doing something, it's helpful to train an incompatible behavior (this I learned from Karen Pryor). However, sometimes it's hard to know what that incompatible behavior should be.

Of course, you also have to see the existing behavior as a problem in the first place in order to want to change it. 

I've noticed that many students who struggle in math are finger-counters. In other words, they use their fingers to add and subtract numbers. This does not seem to me to be a coincidence. In order to figure out a solution, I had to delve into why the finger-counting was happening and why it was a problem.

Happily, as usually happens, the root of the problem was also the source of the solution. The incompatible behavior had the added benefit of being hands-on.

This post will explain my reasoning and help you take the first step to help someone overcome the habit of finger-counting when performing addition and subtraction tasks.