Multiplicative group of integers modulo n ($(\mathbb{Z}/n\mathbb{Z}{)}^{\times }$)

The multiplicative group of integers modulo \( n \), often denoted as \( (\mathbb{Z}/n\mathbb{Z})^* \) or \( U(n) \), is the set of integers that are relatively prime to \( n \) under the operation of multiplication, with the multiplication performed modulo \( n \).