Saving and calculating brewer's yeast for home-brewed beer. Part 1.

I will tell you and show you how to save money on yeast for home beer. We calculate the rate of seeding of dry yeast, prepare the starter and dilute it on a magnetic stirrer...
A little time spent and a more stable fermentation result and, of course, financial savings!
This is the first part-the dilution of half the norm of yeast.
The second part, how to save brewer's yeast, is regeneration or washing and reuse.