Anyone want to help me with some math?

If I want to experiment with post fermentation gypsum additions and I only have a scale that reads 1 gram or more (no decimals) I will need to dilute a much larger amount of gypsum with something else so that I can realistically measure a given amount into my pint glass (or 1 pint mason jar, or whatever).

So I will boil and chill say 100 ml of filtered or RO water (RO probably better) and add ?? grams of gypsum. I will then add ?? ml of the resulting liquid to my 2 fluid oz of beer and taste. When I achieve the desired flavor profile I will multiply the ?? grams of gypsum represented by the ?? ml of solution by 320 to get the amount to add to the keg.

so:

gypsum_{5 gallons} = 320 * ((gypsum_{100 ml}/100ml)*solution_{2 floz})

simplify:

X = 320 * ((Y/100)*Z)

Where X is the total amount of gypsum for 5 gallons of beer, Y is the grams of gypsum added to the 100 ml of water, and Z is the ml of solution added to the sample 2 floz to achieve the flavor profile I want.

Is this right?

what would be a good place to start in terms of how many grams to dissolve in the initial 100 ml of water?