I figured out the 'math' for making a crocheted ball. Okay, I figured it out for my own self. Experts probably already know. It's actually 'stupid easy.' If you can crochet in the round, you can make a ball.
I start with two chains, then do six single crochets in the second chain from the hook.
Next round is two scs in each sc, so you end up with 12.
Round 3: two scs in one sc, then 1 sc (2+1 around) You'll end up with 18
Round 4 : two scs in one sc, then 1 sc and 1 sc (2+1+1 around until you reach 24.)
Okay, so let's say this is as far as you. You have four rounds.
You'll now crochet 4 more rounds of 24.
Then you'll start decreasing. You want to go from 24 back down to 18, so you need to lose 6 stitches. You added them when you did 2 scs in 1 sc. Now you'll crochet 2 scs together, then do a single and a single. (2 together+1+1, which gives you 3) Keep count until you get to 18.
From 18, you reduce to 12. So you'll crochet 2 together, then 1. (This is where I put the stuffing in, but you can do it at any point that is easy for you.)
Finally you're back to 6 again. Simply crochet 2 together all the way around. Fasten off, leaving a long tail. Weave the tail through and pull it tight. Weave in the ends.
The math is basically this: however many rounds you make, you will continue with that many even rounds before reducing. Five rounds will give you 30 stitches around. So you'll do five more rounds of 30 stitches, then you'll start reducing. Just remember you want to lose 6 stitches each round.