Neliöresiduaa
Neliöresiduaa is a mathematical concept in number theory dealing with the remainders of squares when divided by a given integer. Specifically, an integer 'a' is called a quadratic residue modulo 'n' if there exists an integer 'x' such that x^2 is congruent to 'a' modulo 'n'. This is written as x^2 ≡ a (mod n). If no such integer 'x' exists, then 'a' is called a quadratic non-residue modulo 'n'. The integer 'n' is called the modulus.
The study of quadratic residues is closely tied to the solvability of quadratic congruences. For example, when
The concept is fundamental in understanding the properties of integers and their relationships under modular arithmetic.