The multiplicative group of all complex $2^n$-th roots of unity, where $n = 0 , 1, 2 , \ldots$
90591
On the group of all complex roots of unity whose orders are powers of $p$, prime number
143069
What are the direct summands in $\mathbb{Z}^n$?
43058
If $n > 2$, prove that the order of the multiplicative group of units modulo n, $U_n$, is even.
98507
$\text{Aut}(F)$ is isomorphic to the multiplicative group of all $n\times n$ matrices over $\mathbb Z$
116360
Sum of n-th roots of unity
41312
Question on primitive roots of unity
7891
Sum of nth roots of unity
35034
Multiplicative inverses for $Z_n$
109760
Showing that the product of all $n$th Roots of Unity is $(-1)^{n+1}$
68915
What are the units in $\mathbb{Z}[\root 3 \of 2]$?
110416
Sums of roots of unity
86807
The units of $\mathbb Z[\sqrt{2}]$
150822
Finding $\sum_{k=0}^{n-1}\frac{\alpha_k}{2-\alpha_k}$, where $\alpha_k$ are the $n$-th roots of unity
145112
Show that the multiplicative group $(\mathbb{Z}/p\mathbb{Z})^*$ is cyclic
90273
Primitive roots of the unity in $\mathbb C$
11000
Fundamental group of $\mathbb{R}^2 \setminus (\mathbb{Z} \times \{0\})$
4648
Proving that $\mathbb{Z}_m\oplus \mathbb{Z}_n \cong \mathbb{Z}_d\oplus \mathbb{Z}_l $ as groups, where $l=\mathrm{lcm}(m,n)$ and $d=\gcd(m,n)$