Arithmetic is a branch of mathematics which deals with numbers and their basic properties under the operations of addition, subtraction, multiplication, division, and exponents as well as percents, radicals, fractions, and decimals.

In general, more basic properties of the integers belong to arithmetic while deeper or more difficult results belong to number theory, but the boundary is not extremely clear. For instance, modular arithmetic might be considered part of arithmetic as well as part of number theory.

One of the earlier arithmetic devices was the abacus.

According to Wikipedia, Arithmetic comes from the Greek word arithmos, "number" and tiké [téchne], "art")