For how many distinct congruence classes $[a]$ modulo $631$ will there be integer solutions $x$ to the congruence $x^2= a \pmod{631}$.
41890
How to get all solutions of $x^2 \equiv$ $a$ mod $p$?
4972
Mod of numbers with large exponents [modular order reduction]
105225
Number Theory: Complete set of residues modulo $n$
30045
Solving linear congruences by hand: modular fractions and inverses
38285
What is $(65!)^2$ congruent to mod $131$?
15314
Number of solutions to $x^n \equiv 1 \mod p$
107990
Does there exist an integer $x$ satisfying the following congruences?
131941
Solve quadratic congruences.
94965
Solve $x\equiv 1\pmod2$, $x\equiv 2\pmod3$, $x\equiv 3\pmod4$, $x\equiv 4\pmod5$, $x\equiv 5\pmod6$ and $x\equiv 0\pmod7$
145617
Is there any simple trick to solve the congruence $a^{24}\equiv6a+2\pmod{13}$?
19071
solution set for congruence $x^2 \equiv 1 \mod m$
82571
Number of solutions of $x^2=1$ in $\mathbb{Z}/n\mathbb{Z}$
112575
Finding integer solutions of $m^2-n^5 = m - n$
14809
Existence & uniqueness of solutions of linear congruences $\ cx\equiv b\pmod m$
22029
Solving modular arithmetic questions
36713
Solving multiple congruences by CRT = Chinese Remainder Theorem
45882
Solving a congruence without Fermat's little theorem