The lecture notes "Introduction to Modular Representation Theory" by Zhiyuan Bai (https://zb260.user.srcf.net/notes/III/modrep.pdf) contain this gem:

$$\textbf{Lemma 5.1.} \text{Gal}(K/\mathbb{Q}) \cong (\mathbb{Z}/m\mathbb{Z})^\times. \\\text{Proof. Ask a toddler on the street.}$$