This document provides an overview of the abacus and how it is used to perform mathematical calculations. It describes the basic components and functions of the abacus, including how beads are moved to represent numbers and perform addition. Different methods for addition using the abacus are explained through examples, such as simple addition, combined adding and taking off beads, and more complex scenarios involving multiple bead movements. The purpose is to familiarize readers with the traditional abacus tool and how it has been used for mathematics.