percent error formula= |experimental value -accepted value| / |accepted value| * 100%

% error = |0.846 g/mL - 0.78948 g/mL| / |0.78948 g/mL| *100% = 7.31 %

Is 7.31% correct or was there a calculation mistake?

I got 7.159

but perhaps your skills of button-pushing are better than mine