Euler's criterion

English Etymology Named after Leonhard Euler (1707–1783), Swiss mathematician and physicist, who devised the criterion in 1748. Pronunciation en /ˈɔɪ̯.lə(ɹ)z kɹaɪ̯ˈtɪ.ɹi.ən/ /ˈɔɪ̯.lə(ɹ)z kɹɪˈtɪ.ɹi.ən/ Proper noun en number theory A theorem which states that, given a positive integer a which is coprime to an odd prime number p, a is a quadratic residue of p if and only if is congruent to 1 modulo p. Usage notes The calculation on the left side of the congruence — or the result thereof — can be denoted with the Legendre symbol. en eponyms