the original doc has the math, the csv only has the pre-calculated numbers

you cant recover lost data by just resaving in another format lol

As soon as you convert from an .XLS file to a .CSV file, the data and sig figs used to display that data are saved while the math formulas used to calculate that data are erased.

This means that when you try to go from .CSV to .XLS, Excel doesn't know the original formula that created the data to then be able to display more decimal points. The formula is absolutely necessary to change sig figs of displayed data.

The only other way I can think of that would allow one to change sig figs in .CSV data is if the .XLS file was converted with like the maximum number of sig figs displayed, or let's say 10-20. Then in a .CSV, you can modify the sig figs to something less, like 0-20.

But I want to say that if you save that .CSV file after the sig fig change, where you original converted it with 10-20 sig figs but then changed them to 0-20, the .CSV overwrites the data and you lose the sig figs that you concatenated.

Result: adding decimal points in a .CSV isn't possible.

I think you misunderstood the problem.