There are many tutorials and teachers, online and off, that can teach you how to work with matrices. This post is a quick reference for the basics. **Matrix** operations are important in quantum mechanics, so I thought a Sideband might have some value.

I’ll mention the technique I use when doing **matrix multiplication** by hand. It’s a simple way of writing it out that I find helps me keep things straight. It also makes it obvious if two matrices are compatible for multiplying (not all are).

One thing to keep in mind: It’s all just adding and multiplying!