Consider the following infinite series:
(i) $$\sum_{n=1}^{\infty} \frac{1}{3^n}$$,
(ii) $$\sum_{n=1}^{\infty} \frac{1}{2^n}$$,
(iii) $$\sum_{n=1}^{\infty} \frac{1}{n^2}$$, and
(iv) $$\sum_{n=1}^{\infty} \frac{1}{n}$$.
Rank these series in order of convergence speed from fastest converging to slowest converging (with divergence being the slowest).