An abacus is a form of manually operated counting aid. It has originated in China over 2,600 years ago. It is one of the most important inventions of ancient China. The abacus used to be the most widely used calculation tool before the appearance of Arabic numerals. At present, abacuses continue to be used in parts of Asia and the Middle East, especially in the shops, and they are available in stores which stock Chinese or Japanese goods. In the West, it is sometimes used to help young children grasp numbers, and some mathematicians enjoy experimenting with the abacus to work out simple arithmetical problems.