Question

Peace be upon you, Rabbi Michi!
How are you on such a warm day?
I was looking into the measurements and prescribed quantities for various things, and I don’t know whom to follow. Meaning, who is more precise.
Between Maimonides and Rabbi Chaim Naeh there aren’t many differences (at least in the metric method). Between the Chazon Ish and the others there is a really big difference.
I was told that each one is right according to his own method, and that sounds strange to me. In mathematics and in Jewish law there is no pluralism. If I calculated 3 squared and someone else also calculated 3 squared, and one of us didn’t get 9, there’s a problem.
Let me say up front that I really have no idea how each of them arrived at his calculations. I just want to know who is the most mathematically precise; maybe you know. That way I’ll know whom to follow.