When ten pebbles were collected in the right groove they were removed and one pebble was added to the left groove. Soon, however, even this kind of computer was not enough to keep track of man's calculating, and so the abacus was developed. Eventually the board was replaced by a frame, the grooves by wire, and the pebbles by beads. More than three grooves or wires were attached to the abacus allowing man to count to higher numbers. Different versions of the abacus appeared in many countries and are still being used in many places.
People using the abacus for calculations can become extremely skilled in rapid computation.
In some tests, an expert using an abacus has proven to be faster than a person using a mechanical calculator. The abacus remained the only computing device for over 4,000 years. Tables of numbers were developed by the Greek and Roman cultures as well as the Mesopotamian and the Egyptians. However, the abacus still remained as the only calculating device. Arab, Hindu, and European mathematicians were the first to develop techniques of written calculation.