778.79% is the change from 99 to 870
Calculation steps:
[( 870 - 99 ) ÷ 99] x 100 = 778.79%
Formula
Percentage change = [(870 - 99) / 99] x 100
Subtract the new number by the original number
870 - 99 = 771
771 ÷ 99 = 7.787878787878788
7.787878787878788 x 100 = 778.79%