-9.89% is the change from 910 to 820
Calculation steps:
[( 820 - 910 ) ÷ 910] x 100 = -9.89%
Formula
Percentage change = [(820 - 910) / 910] x 100
Subtract the new number by the original number
820 - 910 = -90
-90 ÷ 910 = -0.0989010989010989
-0.0989010989010989 x 100 = -9.89%