The associate
of , where is an odd prime, is a positive number such that (i.e., does not divide), and
is one of the numbers 1, 2, 3, ..., , is the unique number such that
with (Hardy and Wright 1979,
p. 67). If ,
then is called a quadratic
residue of .
of 
, where 
is an odd prime, 
is a positive number such that 
(i.e., 
does not divide 
), and 
is one of the numbers 1, 2, 3, ..., 
, is the unique number such that
(Hardy and Wright 1979,
p. 67). If 
,
then 
is called a quadratic
residue of 
.
