-97.44% is the change from 821 to 21
Calculation steps:
[( 21 - 821 ) ÷ 821] x 100 = -97.44%
Formula
Percentage change = [(21 - 821) / 821] x 100
Subtract the new number by the original number
21 - 821 = -800
-800 ÷ 821 = -0.97442143727162
-0.97442143727162 x 100 = -97.44%