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In the ancient civilizations of Egypt, Rome, and China, pencil and paper were luxuries and the numbering system was clumsy. Therefore, calculations were carried out using counting stones and rods. In fact, the Latin word for pebble, calculus, is the origin of the modern term calculate.

In its earliest form, the abacus was a board which was incised with a series of parallel grooves. Calculations were carried out by sliding pebbles back and forth in the grooves. In a later development, beads were strung on wires or thin strips of bamboo, reducing "crashes" and making the operation of the abacus less clumsy. 

The most familiar form of the abacus was developed in China during the sixth century. The counters of this abacus (the suan pan) are divided into two sets, one set representing fives and the other set representing ones. This arrangement simplifies carrying while adding and borrowing while subtracting. 

With the introduction of Arabic numerals, the popularity of the abacus began to decline. The modern computer has only served to hasten its demise. However, the abacus still sees limited use in schools, where it is used to demonstrate numbering systems and the theory behind simple arithmetic operations.