What is the order of $\mathbb{Z}_2\times\mathbb{Z}$?
For $\mathbb{Z}$ every non-zero element has infinite order, then $\mathbb{Z}$ has infinite order. Otherwise $\mathbb{Z}_2$ has order 2. Then what is the order of $\mathbb{Z}_2\times\mathbb{Z}$? Is infinite order?
Why $\mathbb{Z}$ has infinite order?