When you test convergence or divergence of an infinite series (with positive terms), are you unsure which convergence test is the right one to apply? I'll show you how to use the highly intuitive concept of rates of growth to do all the hard work! After that, it's easy to use one test, the comparison test, to check convergence or divergence of most series of positive terms. This approach is fast, fun, easy, elementary, and the most mathematically satisfying way to do most convergence testing of series in calculus.