With respect to a relation , an equivalence class has three properties. Take as an example the integers modulo 3 with respect to congruence.
1. Reflexivity: . For example, modulo 3, .
2. Symmetry: implies . For example, modulo 3, and .
3. Transitivity: and implies . For example, modulo 3, , and .
The equivalence classes of the integers modulo can be represented as segments of a wheel, with the congruence class of each of the integers shown. Given a positive integer , each integer satisfies the formula , where . Here is the value of the equivalence class (shown over-lined), is the order of the additive group and is the segment, starting from 0 in the innermost circle.