The degrees of the irreducible characters are divisors of the order of $G$

Let $G$ be a finite group into the field $mathbb{C}$, then the number of irreducible characters of $G$ is equal to the number of conjugacy classes of $G$, and there is the relationship

$$|G|=sum_{1le ile k}n_i^2$$
where $k$ is the number of irreducible representation of $G$.

Result: The degrees of the irreducible characters are divisors of the order of $G$.

I thought that with the facts above I can prove this result, but I couldn’t, This result seems trivial (I can be wrong), can someone help me?