Arithmetic is a branch of mathematics that deals with numerical computation— specifically computation using integers, rational numbers, real numbers, or complex numbers—with the computations simple to complex. The word arithmetic has its roots in the Greek word for “to count” (arithmeein; also arithmos, or “number”).

Arithmetic contains all the rules for combining two or more numbers. In most cases, when mathematicians talk about elementary arithmetic, they are speaking of those subjects most of us learned in grade school: addition, subtraction, multiplication, and division being the most common; and fractions, geometry and measurements, ratios and proportion, simple probabilities, and algebra examined in more advanced levels. For even more advanced students, such arithmetic lessons as congruence calculation, root extraction, power computations, and advanced factorizations are often presented.