oneven

Oneven is a Dutch term used to describe two related ideas: odd numbers in mathematics, and things that are not even or level in a general sense.

In mathematics, an odd number is an integer not divisible by 2. Examples include 1, 3, 5, and 7. An odd number leaves a remainder of 1 when divided by 2. Every odd number can be written in the form 2k+1, where k is an integer. Parity rules include that the sum of two odd numbers is even; the sum of an odd and an even number is odd; the product of two odd numbers is odd; multiplying by an even number yields an even product. In modular arithmetic mod 2, odd numbers are congruent to 1 and even numbers to 0. Odd numbers form an infinite sequence and have important applications in number theory, combinatorics, and computer science.

Beyond numbers, oneven is also used in everyday Dutch to describe non-smooth or irregular features, such as an uneven surface or an uneven distribution. For describing roughness, the adjective oneffen is more common, while oneven remains standard for the sense of odd numbers. The term is closely linked to the broader concept of parity, a foundational idea in various areas of mathematics.

In educational contexts, oneven appears alongside even numbers as part of basic arithmetic and introductory number theory. Together, parity concepts help explain divisibility, modular arithmetic, and patterns across integers.