Units mod $n$ is a well-defined set
66748
Show that if $a \equiv b \pmod n$, $\gcd(a,n)=\gcd(b,n)$
95294
Dense subset of $C[0,1]$ which preserves rationals
103427
When is $\operatorname{Hom}_A(M,N)$ finitely generated?
92583
Prove that $N(\gamma) = 1$ if, and only if, $\gamma$ is a unit in the ring $\mathbb{Z}[\sqrt{n}]$
151928
How to prove that $N\setminus A$ is finite?
108922
Cardinality and infinite sets: naturals, integers, rationals, bijections
144362
The construction of a Vitali set
87830
Relating the union of the power set of a set to the set itself
139826
arbitrary large finite sums of an uncountable set.
67926
$S_n$ is generated by elements of the form $(1k)$
62996
A problem regarding the proof of ${p^nk\choose p^n}\equiv k\mod p$, where $p\nmid k$.
81150
Positive integer multiples of an irrational mod 1 are dense
29204
$a\equiv\bar a\!\pmod{\!kn}\Rightarrow a\equiv\bar a\!\pmod{\! n};\ $ $(a\bmod kn)\bmod n=a\bmod n.\ $ Congruences persist mod factors of the modulus
47709
If $n\mid m$ prove that the canonical surjection $\pi: \mathbb Z_m \rightarrow \mathbb Z_n$ is also surjective on units
149673
Cardinality of an infinite union of finite sets
138670
If product of finite elements in a ring is a unit then can we say each element as unit
12469
$\varphi$ in $\operatorname{Hom}{(S^1, S^1)}$ are of the form $z^n$