example of divisible group

Let $G$ denote the group of rational numbers taking the operation to be addition. Then for any $\frac{p}{q}\in G$ and $n\in {\mathbb{Z}}^{+}$, we have $\frac{p}{nq}\in G$ satisfying $n\frac{p}{nq}=\frac{p}{q}$, so the group is divisible.