Why are you going through all the math? Durvet’s plunger has the dosage engraved on it. Dial in your weight, upcap the tube, put it in your mouth, squeeze the plunger, done.
More details:
https://freerepublic.com/focus/news/3991731/posts?page=50#50
Because that dosage is for deworming a horse. Different mammal, different purpose. Turns out, double the horse weight should be dialed in for covid treatment. The same weight should be dialed in for preventative/prophylaxis. I’m not using it as a preventative so I would need double the horse weight for treatment purposes.