Try "=((0.1+0.2)-0.3)*1e80" -- your test can be fooled by pretty standard rounding for display.

That could be just the way it's displaying, e.g. to 14sf or something. If you try adding a million 0.1s and use a formula to compare to 100,000, that might tell you (with floats I got 100000.00000133288).

This question suggests it uses floats: https://stackoverflow.com/questions/74542790/google-sheet-yi...