Arithmetic is the most elementary branch of mathematics. It involves the study of quantity, specifically the four fundamental operations of arithmetic: addition, subtraction, multiplication, and division (see also arithmetical signs). Also included under the umbrella of arithmetic are exponentiation and the extraction of roots (square roots, cube roots, etc.). Arithmetic is sometimes described as including number theory, but the latter is best considered as a separate branch of mathematics.
While arithmetic is the most elementary branch of mathematics, it is also the most widely used and the most fundamental. Some knowledge of arithmetic is necessary for every profession and for day-to-day living. Furthermore, an understanding of arithmetic is necessary in order to understand algebra or geometry or any other more advanced branch of mathematics.
If you're interested in learning how to perform arithmetic faster, see calculation shortcuts.
See also laws of arithmetic or arithmetic tricks.
Sources used (see bibliography page for titles corresponding to numbers): 43.