arithmetic

Short definition from Wiktionary

Noun

1. 1
   The mathematics of numbers (integers, rational numbers, real numbers, or complex numbers) under the operations of addition, subtraction, multiplication, and division.
2. 2
   Number theory

Adjective

1. 1
   Increasing or decreasing by an arithmetic progression.
2. 2
   Of, relating to, or using arithmetic; arithmetical.
3. 3
   Of a progression, mean, etc, computed solely using addition.