The abacus is a fun tool to do math with. It helps you learn all about the base ten system (which is the one we use for ordinary math), patterns among numbers, and how to do math in your head. It is probably the best tool in the world for most people to get a good grasp of numbers with.
Why should i learn to use an abacus when can a calculator is one of the questions hear most people think that just some exotic toy would be like calling galileo italian guy.
The main reason to learn how to use an abacus, is because it will teach you how to manipulate numbers - how each digit relates to the others, and how to use that knowledge to get very good at understanding how to do all the major operations - addition, subtraction, multiplication, and division.
The abacus will also give you a handle on how base systems work. For instance, you can use an abacus to do math in the decimal system (which we use in everyday math) and the binary system (which is used in computer science).
Understanding decimals becomes a breeze when you know how to use an abacus. Exponents and square roots can also be done with a little practice.