-88.92% is the change from 821 to 91
Calculation steps:
[( 91 - 821 ) ÷ 821] x 100 = -88.92%
Formula
Percentage change = [(91 - 821) / 821] x 100
Subtract the new number by the original number
91 - 821 = -730
-730 ÷ 821 = -0.8891595615103532
-0.8891595615103532 x 100 = -88.92%