# Revision history of "Congruence condition for minus one to be a quadratic residue"

• (cur | prev) 15:26, 21 April 2009Vipul (Talk | contribs). . (301 bytes) (+301). . (Created page with '==Statement Suppose $p$ is an odd prime. Then, $-1$ is a quadratic residue modulo $p$ if and only if $p \equiv 1 \pmod 4$. Equiva...')