Why is $a^{-1} \cdot a \equiv 1 \text{ mod } m$ a lemma in universal hashing?
7043
mod [= remainder] operation (and relation), name and meaning
139659
Find all $n$ with $\!\bmod n\!:\, a\,$ invertible $\Rightarrow a^{-1} \equiv a,\,$ i.e. $a^2\equiv 1$
111505
Proof $\binom{p-1}{k}\equiv (-1)^k \mod{p}$
16548
Prove $(x+y) \text{ mod } n = ((x \text{ mod } n)+(y \text{ mod } n)) \text{ mod } n,\,$ and product analog
114519
An elementary question regarding a multiplicative character over finite fields
148458
$x^p-x \equiv x(x-1)(x-2)\cdots (x-(p-1))\,\pmod{\!p}$
100720
Negative quotients and their remainders
82921
Uniqueness of $k$th root mod $m$ if $(k, \phi(m)) = 1$.
121732
Functional completeness of $\{\text{or},\text{ xor}, \text{ xnor}\}$
68252
Chinese Remainder Theorem solvability for non-coprime moduli
30725
Why are naturals < modulus equal if congruent? [uniqueness of remainder]
103578
Affine cipher : Why it is required to have GCD(a, m) equals to 1
55621
Show that if $c_1, c_2, \ldots, c_{\phi(m)}$ is a reduced residue system modulo m, $m \neq 2$ then $c_1 + \cdots+ c_{\phi(m)} \equiv 0 \pmod{m}$
58803
${n \choose k} \bmod m$ using Chinese remainder theorem?
52461
Why does $(g^b \bmod m)^a \bmod m = (g^a \bmod m)^b \bmod m$?
156089
Why is the associative property valid for modular arithmetic?
667
Why use $(r,s)$ instead of $(r,s^{-1})$ as DSA signature?