If a number is congruent to $ 1\mod 4$ or $0 \mod 4 $ , does it mean the number is a square?
24601
Proving that a natural number made entirely of 6's and 0's is not a square.
57654
Congruent Modulo $n$: definition
8784
modulo version of the quadratic formula and Euler's criterion
55357
Why does drawing $\square$ mean the end of a proof?
79208
Is the number $-1$ prime?
125702
There is a square $Q$ consisting of $(0,0), (2,0), (0,2), (2,2)$
33184
Something strange about $\sqrt{ 4+ \sqrt{ 4 + \sqrt{ 4-x}}}=x$ and its friends
43453
Is ${\sqrt2^{\sqrt2^{\sqrt2^{\sqrt2^\sqrt2}}}}^{...}=4$ correct?
126725
If $p$ is prime and $p$ $\equiv$ $1$ (mod 4), then the congruence $x^2$ $\equiv$ $-1$ (mod $p$) has two incongruent solutions...
67899
Integer squares of the form $x^4+x^3+x^2+x+1$
9092
What is special about square numbers here?
110608
What is $\,a\bmod 63\,$ if $\,a\,$ is both a square and a cube?
124279
$g^k$ is a primitive element modulo $m$ iff $\gcd (k,\varphi(m))=1$
96398
An integer $a \pmod m$ has inverse if and only if $\gcd(a,m)=1$?
138081
How to determine whether a number can be written as a sum of two squares?
79103
Check if a number is a perfect square
96535
Show that if $\gcd(a,3)=1$ then $a^7 \equiv a\pmod{63}$. Why is this assumption necessary?