Since $G$ is abelian of order $30$ we have that $$G \cong \mathbb{Z}/2\mathbb{Z} \times \mathbb{Z}/3\mathbb{Z} \times \mathbb{Z}/5\mathbb{Z}$$ $$\text{Aut}(\mathbb{Z}/p\mathbb{Z}) = p-1, \text{ p prime} $$ does that mean $$|\text{Aut}(G)| = 1\cdot2\cdot4 = 8$$ or is it false that $$\text{Aut}(\mathbb{Z}/2\mathbb{Z} \times \mathbb{Z}/3\mathbb{Z} \times \mathbb{Z}/5\mathbb{Z}) \cong \text{Aut}(\mathbb{Z}/2\mathbb{Z}) \times \text{Aut}(\mathbb{Z}/3\mathbb{Z}) \times \text{Aut}(\mathbb{Z}/5\mathbb{Z})$$
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See also this post for problems arising if two primes or coincide, i.e., are not coprime. – Dietrich Burde Jan 25 '22 at 09:13