We will talk about Liouville numbers and some of their properties under certain maps. For instance, if t is a Liouville number, then cos t is a transcendental number. While this is not (entirely) surprising, one often needs to resort to deeper results from transcendental number theory to deduce such. We will demonstrate a fairly elementary method of achieving the same conclusion. We will then pivot to a more "global" perspective, and take a fresh look at an old remarkable theorem of Erdos. The talk will be elementary and no prior exposure to (transcendental) number theory will be required.