How many invertible elements are there in $\mathbb {Z_ {990}}$ and $\mathbb {Z_ {1060}}$.
58188
What's the proof that the Euler totient function is multiplicative?
46110
how many 2x2 matrices are invertible in mod p
86807
The units of $\mathbb Z[\sqrt{2}]$
51695
Finding all homomorphisms between $\mathbb{Z}/m\mathbb{Z}$ and $\mathbb{Z}/n\mathbb{Z}$
119648
For which $n$ and $k$ are there nontrivial homomorphisms from $S_n$ to $\mathbb{Z}/k\mathbb{Z}$?
46971
Number of surjections from $\{1,...,m\}$ to $\{1,...,n\}$
30456
The number of $2 × 2$ invertible matrices with entries from field $\mathbb{Z}_p$
8494
Proof Check: Number of elements of $\mathbb{F}_{p^{n}}$ of the form $a^{p}-a$ for some $a \in \mathbb{F}_{p^{n}}$.
84132
Number of preimages of a group element under a homomorphism.
35034
Multiplicative inverses for $Z_n$
157915
Isomorphism between the group $(\mathbb Z[x], +)$ and $(\mathbb Q_{>0}, .)$
30172
Why is the order of $\mathbb{Z}[i]/\langle 3+i\rangle$ equal to 10?
133019
Nilpotent elements in $\mathbb Z_n$
143069
What are the direct summands in $\mathbb{Z}^n$?
107010
How many elements of order $k$ are in $S_n$?
67208
Can we say that there exist an integer $n$ such $A+nB$ invertible?
26661
Ring homomorphisms from $\mathbb{Z}_n$ to $\mathbb{Z}_m$