An adding device is a tool used to perform mathematical calculations. The two most common examples of adding devices are the ABACUS and the ZERO. The ABACUS is an ancient counting tool that consists of a frame with beads strung on wires. It is still used in some parts of the world today. The ZERO is a more modern invention, which is a symbol used to represent the number ZERO. It is used in many different numerical systems and is essential for performing calculations.