yeast - just how much is in there?

I googled and got a couple of answers:

1. It takes 20,000,000,000 (twenty billion) yeast cells to weigh one gram or 1/28 of an ounce.

1. One pound of yeast contains 3,200 billion yeast cells!

Expanding the first estimate to an ounce: 20 billion X 28 = 560 billion per ounce. The second one gives: 3,200 billion / 16 = 200 billion per ounce. So if you throw in an ounce, you're dealing with hundreds of billions to start. Since the growth is exponential, you probably end up with trillions.

Paul

Just to divert the thread a bit. Is there a way of preserving yeast? Obviously the big commercial people do because they sell dried yeast. But how do you make it?