Read this tip to make your life smarter, better, faster and wiser. LifeTips is the place to go when you need to know about Amigurumi and other Crochet topics.
To create a flat circle with single crochets, start with 6 scs and increase 6 scs in each round so that the total stitch count in each round is a multiple of 6. With hdcs, it's a multiple of 8, and dcs are multiples of 12. If you increase the number of stitches per round faster than these multiples, the edge will start to ruffle like a hyperbolic plane; if you increase the stitch count more slowly, you'll be making a dome.